I see no problem on driving a tractor on the road. Today, I saw at least 20 tractors on the road on a simple 65 km trip, and I got "stuck" behind a couple of them too, no big deal though. Saw a couple 25 hp tractors, a bunch of 30 to 60HP and some bigger 120 HP+ tractors, mostly loggers pulling the logging trailer, some empty, some full. Other with the brush mowers, being that's mowing season now.
However, I do understand that this be more of a problem in the US than Europe because of the citiots. We have them too, although, very very rare. People are usually very conscientious and respectful.
Just make sure you're visible. Plenty of flashing lights and SMV sign.
Before I got the pickup truck, I used to just drive my tractor to the pet food store to buy crushed corn and a couple bales of hay for the goats and chickens. I do enjoy driving the tractor on the road.