As for streets, the only issue really is height. Most full profile 5er's now are 13'6" tall, so low bridges, trees, etc can be an issue. a 40' 5ver wont get into all the same campgrounds as a 30'. You have to determine what type of camping you prefer, and the places that you would go. Many of the state parks have a reservation system that will block out sites, based on length, so you can get an idea of site availability by length.
We went from a 30' TT to a 40' 5th, and have no issues with any place that we normally camp.
the only other issue to think about is fueling when on the road. You don't want to pull into a tight gas station, or low overhang. When we are on extended trips, I try to use the busier truck stops, and either use the truck lanes, or in the case of pilot/flying J, many have special RV lanes.