Consider where you will be camping. Commercial parks won't be an issue. National Parks will have limited spaces for longer trailers. National Forests will pretty much be out of the question. Most of these have sites designed many years ago when trailers were smaller. They cannot accommodate the larger RVs of today.
Other parks will be a mixed bag. The California state parks in our San Diego,mountains have very few spaces that can handle long trailers. The state parks at the beaches are fine though.
With a long trailer a longer tow vehicle will make towing easier so consider the bed length when looking at a truck.