i never had an issue with needing chains with my trucks, or friends cars/suvs, 4wd always fixed any traction issues for me, good tires in snow are a must, and i think a law now on I-70
hoosier pass can be sketch in the winter, as i am sure you know,
to be honest, for what you want to haul and how far, a 1 ton or 3/4 ton diesel may be overkill, if they are in your budget a 1/2 ton Ram may be a good option with the 3.0 liter diesel, or even a gas truck would probably work
you are towing the boat on mostly flat land, two snowmobiles are not heavy - maybe 2-3,000 lbs with trailer? a friend would tow a single sled up the mountains in a tacoma for reference.
let us know what you decide