DO NOT DO 441 WITH A BIG TRAILER. It is steep and very curvy. I see class C's with burned up brakes all the time on the Gap road. It would be a workout towing a big trailer and you better have some mountain towing experience behind you if you do take it on.
Do the 40 to 26 route. SO much easier. I have a 37 ft. trailer and I don't even try to go over the Gap....I go around. Take Veterans Parkway out of Pigeon Forge....that's the road Dollywood is on. Go up to 411 and head east. It will connect to 40. There will be a short distance with some curves and a slight downhill grade and it goes by the Bush's bean plant and visitor center. Lots of room for a trailer to park and go in the visitor center. Then the road opens up to a new 4 lane divided Hwy. all the way to 40. (40 is a right turn when you hit 25/70, 411 ends there)
As far as going through the Pigeon River Gorge just fall in with the trucks and follow them. It's up hill for about 20 miles but not terribly steep, but steep enough to keep your foot heavy on the gas pedal. Pass the trucks if you have to. There are 2 tunnels that have plenty of height so don't worry when you see the sign.....take up both lanes if you have to to go through the middle if you're more comfortable with that. I have no trouble with my 2500 and my trailer...10KGVWR.