Think about the real risks with any sort of click stand etcWhen, not if, his bike falls over, in his own words, the mounting attachment will be overstressed, as he can't lay the bike down all the way.
Heck just the other day I stopped at a small airport to look at some WW2 aircraft being wheeled into a hanger, leaned my commuter bike with two heavy panniers on it against a fence, and a big gust of wind funneled through the hanger and air museum toppled it over, kabang!
But ya, cf and stands are just asking for trouble.
I'd argue that applies to any kick stand. I've seen my buddies who claim their bikes never blow over with their kick stands do just that more times than I have seem my own non stand equipped bikes blow over. The question remains, what is the OP to do? Always lean the bike against someting if he can and unhitch it when he can't?
Will the bike really not stand with it jacknifed 90 degreees some setups will and some won't. Maybe changing out the tongue on his trailer to one that attaches to the seatpostn would allow that?
How far will the bike/trailer jacknife? If far enough maybe some kind of improvised strut between the two would work?