What is the max length travel trailer you think is practical

Our most recent (bought this past summer) is specd at 37'9". Living space is about 35'. It actually tows far better than our old 33' trailer. Definitely tight in some state parks but so far we have gotten it into places we want to go. We considered 5th wheel this time but wanted to keep the cap on the bed of the truck so ruled it out. Don't regret the length and love the space once we are there! Just make sure you have the right truck and hitch setup.