It would depend on when you were planning to stay as far as what sections of the campground would be open which would allow for space for your rig. The RV only loop would have numerous sites where you could fit. If that loop isn't open, I have found the information listed on their website concerning the length of each campsite is fairly accurate.

Getting to the campground shouldn’t be too bad. Like another poster mentioned take US 74 out of Cleveland, TN and take it to Cherokee. There are no climbs, just the gorges along the Ocoee and Nantahala Rivers, plenty of tractor trailers go through them so not a big deal. Depending on when you are going though, Smokemont only has a couple of sites that fit a 38’ camper in the off season when all but the front loop are closed. They are up front across from the dump station. During regular season there is an RV loop for bigger rigs that’s open.

I can't say with certainty the best way coming from the west. If you do take 40 into NC I'd avoid the Blue Ridge Parkway in something that big. I've take a 42 foot rig down the southern BRP, but it was a little scary in spots.

Head over to Chattanooga(probably US72 to Kimball, TN), get on I24/I75 heading to Chattanooga and on to Cleveland, TN. Get on US74 heading east. That should bring you to Cherokee, NC. From there get on New Found Gap road aka US441. It is short distance from Cherokee to entrance to Smokemount. From Cherokee it will be a right turn into campground. When I was there I saw a few Class A 's and several large Class C's.

As long as don’t go through Townsend into Gatlinburg, it should be ok. (We did this route in a sprinter, and wouldn’t recommend that to anyone in anything bigger than a suv). Come in from the Cherokee side. Campground is pretty large with wide turns. Lots of diesel pushers make it in.