Thanks for the comments. Gritdog gave some great advice for homemade overloads, so I am going to try those with timbrens to start and get the Torklift ones if I like the results with the homemade. I think I prefer the system to airbags, although a lot of shops are recommending airbags. They are twice the money to timbrens with install.
I have the weights written down at home, can't remember exactly, camper is 3000 or 3100 lbs with two full propane, battery and partially full water (nothing in black or grey). And yes, without trailer. Looks like I might have to give up on the big trailer for sure.
So I'd bet we'll be 3500-3600 fully loaded.
Rear tires are 3200 each. I am looking at some 18" and 20" that are 3800, then I should have plenty.