I've towed some heavy loads with my half-ton truck, but if you have a bigger truck available I'd encourage using it.
This past summer I pulled a '57 Chevy wagon 1,600 miles on a dolly across Oregon, Idaho, Utah, Wyoming and into Colorado. I stuck to freeways where traffic is faster, but generally everyone is going in one direction, and tried to keep long following distances. Going through Denver was scarey because no one would allow me to keep even a car length between me and the car in front. Otherwise it was fine.
I figured my load was about 3,500 pounds dolly and car combined, because the car had no motor or transmission.
It can be done, but be careful!
