All or any the big 3 diesel one tons will tow fine, there is a difference in GVW because of gear selection. Make sure you get what you need as salesmen/woman do not always know or care about your needs just their commission.
35 ft is not too long for a fulltime fifthwheel. Ours is 35 ft overall and we have no problem finding spots and yes we stay in SP's, FS, and ACE campgrounds as often as possible.
Truth is most fulltime rigs either fifthwheel or motorhomes are longer than 35 ft. There are some that prefer shorter rigs because they want to get way back in the woods but they are the minority.
Bottom line take your time it's cheaper to get it right the first time.