I'm another Smoky Mts. guy, of about 40+ years. Up until about 10 yrs. ago, I went to Cosby or Look Rock. Look Rock is closed and I know of no plans to re-open it. Up until this year, I started going to Elkmont, for about 10 years. My "take" on the place is similar to TT's. I tried to like the place but, I went back to Cosby this last October. If my week there is typical, it has gotten a little busier but, it still seems OK. They repaved the roads and parking spurs recently - which is nice. One "downside" is there are not many RV sites. Most are "tent only". I suggest reserving online the RV sites, as there are few. Cosby closes for the season at the end of October.
Of course, there are no hook ups. Cosby has a dump station near the check in station at the campground. Elkmont has no dump station. The nearest one is across from the Sugarlands Visitor Center - about 7 miles (+ or -) away. If one likes the bling of Gatlinburg/Pigeon Forge, Elkmont is closer. Newport is about 30 mins. from Cosby (I-40) and you can get most anything you would likely need there. Elkmont does have a small camp store & firewood in the campground. Cosby does not. There is a convenience store and gasoline just outside of the park, however.
As far as I know, the only 2 campgrounds, in the Park, that are open year round are Cades Cove and Smokemont.
Site A20 is a good site - if you can get it. It can not be reserved. It is large and on the end of the loop road. It drops sharply from the parking spur (no R-dome) and has a small stream at the "bottom". The map shows it as a tent site (probably due to the drop off) but, your Pod would fit there. My Coleman is roughly the same size. As a bonus, Cosby is less expensive, per night, compared to Elkmont.