That it absolutely will not do. It will lower the amplitude of minor sways and even "hide" the first hints of snaking, but it will not prevent or even minimise a full blown snake. They just make towing more relaxing as they "damp" the harmless minor sways and pitching that are inevitable when towing a trailer.
Despite what the name might infer these so called "stabilisers" are actually only friction dampers and do not "stabilise". They most certainly because they damp the twitching, lower the driving fatigue and comfort but they don't stop or modify the natural frequency to a snake; some including me take the view they can mask the initial hints allowing a situation to develop holding enough energy for things to go wrong quickly. I use the modern one integrated in the hitch as that is what the van was sold with, and I like the way the van "rides"; however I have towed other vans and trailers countess thousands of mile without them and been aware of their twitches. In a away for me a welcomed reminder to be aware. So not having one really makes no difference other than ride comfort, if the situation becomes right for instability they are no help at all. On the other hand the active systems like ATC are very effective, if crudely executed true stabalisers.
I think you have found the lining inspection port plugs, not the adjuster. These things are quite specialised because of the auto reversing mechanism and you need to read and understand how they work and the importance during adjustment not to move the drum in the reverse direction, at all. Also it is important not to adjust up too "tightly", give more freedom than with car drums so the reverse tumbler can "tumble" and so not cause a brake lock up come reversing the van up an incline. Here is a link: http://www.al-ko.co.uk/edit/files/handbooks/overrun-braking-system-handbook.pdf
Try reversing by starting from the level in one unhesitating move; that IME best ensures that the reversing cams do what is intended. Issues seem to be related to the van rolling forward against the towball, just as it "over runs" to apply the brakes as intended in normal forward motion. If you don't allow that braking to relax then they are quite reticent to allow the reversing cams to "trip". Probably not adjusting them up too keenly allows a bit of space for the cams to trip as intended?
Seems their formula works? There is nothing in their rules or pricing that "rub" with us. I have no issue with sites where the owners so obviously have pride and value their operation. If that is what they feel is needed to attract a clientele with the ethos to keep it looking as the photos, that's fine.
A very nice looking place with lovely well tended lawns so I can completely understand their no reversing policy as a caravan or car wheel running over these lawns will really spoil things. I am sure if you have a really easy light to move teardrop they would understand it does not need a mover; their concern is I have little doubt, the damage reversing is well capable of doing. I expect they take much the same flexible view and allow motorhomes to reverse either onto or off the pitches.
Being for the best part of 40 years significant users of 5 van sites in both clubs, so a fair judge on typical occupancy levels any thought of them achieving 75% occupancy is IMO way way off the mark. Many would love to see that just on weekends in summer. Frequently, during the week out of school holidays we find no other user or just one. I recall going to more than one well into the season to be told we were the "first that year". This indicates despite our passion for the camping style they offer, for the vast mass of club members they are not required, which over the years seems even more the case. I suspect very few indeed offer the owner any revenue stream at all, just an expense. Quite a typical comment from farmers is "we do it for a bit of company, otherwise we never see anybody to talk to". What many users don't realise is nowadays on a VAT registered farm, the 5 van site income is charged VAT, even if its the wife's hobby but where she is a partner in the farm ownership. Those on smallholdings and in gardens where the whole is not a VAT registered setup, don't have that extra 20% burden. I come across situations where a farmer is lumbered with adding VAT to his price but another local provider falls outside that and does not.That price difference is enough to drive some price focused clients away. I feel that 5 van sites are a fragile and disappearing facility and I will be very sad if those that follow us don't have that option anymore. Another "coffin-nail" is the trend towards motorhoming where ground conditions on many really don't suit front wheel drive heavy units, which all has to be driven on and off with every "outing", even sightseeing. Plus with them a camping culture of "must be travelling to somewhere else" , and having to move everything off to go visiting so needing no base, the stays are rarely into "nights", just an overnight more often than not.
Nor do we stay on site all day every day but we stay long enough for its "charms" to be paramount, as I said it all boils down to "ones perception of value" and " to what you "value". Clearly a site limited to just 5 units has fewer units to amortise all the infrastructure overhead charges over than one with 10, 20 or more times the unit count. If cheap is what you value, then 5 van sites could well not always meet your goals.
We don't simply look at price, for us what "charm" a site has to us, is of prime importance, not even facilities as we brought a van with all we need. It does not need EHUs for most of the year, we also have our needs there sorted. A big part of "charm" in our opinion is that hopefully it will only have another 4 units at the most and could be a nice open field not tight packed rows of caravans or motorhomes. Then there is a whole host of other "charms", location, views, cycling opportunities and recently the lovely prancing antics of the lambs in the abutting field. I suspect ones perception of value, comes down to what you "value".
I suggest with a need to jack at the roadside for a puncture that you set things up by using your car to haul the deflate wheel well up onto something to increase the chassis height from the ground. Using your blocks etc. This makes using a range of jacks both possible in that you can get them under, and for scissor jacks ease the lifting as in the most squat state they are not very effective so very hard work. Once lifted off blocks remove them to benefit from the clearance getting an inflated wheel in place. I did this with waiting for the recovery chap a couple of years back, he had never come across it and commented it was a great help. Not my idea but one I was told of ages ago and always used when fit enough to do these things myself.
At home it is a big proper garage trolley jack. Away from home it will be whatever my recovery service turn up with. Personally now too old and things too dangerous on roads to take on wheel changing when already paid for that service, plus don't want to carry always the weight of a proper, safe to use, jack. If for on site fitting second lock on twin axle I would use an air bladder under the adjacent locked wheel to unload the second wheel for fitting its lock.