^Great points. And while I can’t argue the virtues of going to stout 16” LT tires IF they’re even remotely warrAnted and fit without any major modifications, the fact remains, the OP can get stout 15” ST 2800lb rated 80psi tires very conveniently and more economically.
And since the OP said his trailer is 8500lbs, there is less than 2000lbs load on each tire. If a 35% increase in tire capacity compared to the load isn’t enough, I’m not sure what’s being gained by up-sizing even more.
Not to mention that virtually any 15” trailer tire made today is actually within capacity for his camper, albeit with less reserve capacity.