However, two things bother me once we get up close to that 40’ mark. One, is the wheelbase on the truck adequate for a TT this long or am I asking for problems? Two, (and I think I know the answer to this) am I going to have problems fitting something this big in a lot of campsites?
The longer trailer will likely tow without much noticable difference. Use some creativity in camp. If you can find a site with no rocks, posts or trees behind the pavement just let the rear hang over the dirt or grass while keeping the wheels on the pavement. Long trailers are doable if you really want to camp somewhere. You might have to ask the neighbor to move their TV for a few minutes while you get positioned, or hold back some bushes, go the wrong way on the one way camp road, etc. Been there done that! But don't let size stop you if that is what you really want. You will always find nay sayers that will try to tell you that something is too hard or can't be done. Hang with the folks that are doing what you want and learn from them.