The size really will limit you in may ways, especially if you're used to a Truck Camper. When we upgraded from an 18 foot box to a 24 foot box TT it kept us out of 20 to 30 percent of the campgrounds I used to be able to get into. Having now moved up to a 36 foot 5er we're probably down to only 30 percent we can still get in to. Due to the comparatively low ground clearance many of the dirt roads I used to roam aren't an option any more. Long and low ends up dragging.
At 36 foot Forest service sites except the ones in the more major built up areas are pretty much not an option anymore. State parks, I can pretty much get into most around here, but you have to book much earlier to have a chance of getting a bigger spot, which a limited in some of our state parks. The height, long turning radius, and lack of maneuverability also make it more difficult to get into many gas stations and the like. If you're on freeways, or major highways you generally have many good options but if you wander off the beaten path often things can get interesting.