Tough question, in 1966 we were driving 440 cu.in behemoths pulling 14 footers; weight was not much of an issue.
Unless someone on the board remembers, I would Google "Vintage Trailer Talk".
Those folk specialize in vintage TTs.
Sorry I could not be of much help.
Good Luck.
Twenty six foot 2010 Dutchmen Lite pulled with a 2011 EcoBoost F-150 4x4.
Just right for Grandpa, Grandma and the dog.