For that year range of Super Duties the only difference between an F250 and F350 is an overload spring on the rear pack and a taller block; should you find an F250 with the "camper pkg" as mine had, you gain the overload spring.
Later model years brought more differences between the 3/4 and 1-tons.
APT wrote:
5er Toy Hauler? Get a dually. They tend to have higher % of pin weight than regular fifth wheel RVs. Plus larger tanks, heavier frames to handle maybe 5000 pounds of cargo.
I can respect that you don't want a dually, but watch your weights very closely; as APT mentions THs are built quite stout and can be heavy heavy heavy.
