Towing a long TT is really a personal issue. It just depends on what type of camping you do. If you're a dry camp type then a long TT will cut your options drastically. If your a full hookup type camper then the options are greater. It also depends on where you camp in the U.S. I know that here in Oregon most of the FS campgrounds are smaller. State CG's can be really small as well. However there are some with large spots. So once again it really boils down to the type and location of your camping habits that will determine how you're going to like towing and camping in a long TT. We towed a 31' TT for 2.5 years and 10,000 miles, while being apr 4' shorter than a long TT we were limited on some spots. Getting gas was never an issue.
JMO but I would not get a 35' TT. I'd go for a 31' 5th wheel instead. Same interior sqft. Shorter overall towing length and easier to fit into more camp spots.