There are several RV parks in the town of West Yellowstone and a couple either direction just outside of West Yellowstone. I know many of our members have stayed at various ones that do accomodate our 5th-wheelers and TVs. I've gone blank at the moment about specific names, but I'm sure you'll get a lot of suggestions very soon.Cody, at the East Entrance of Yellowstone, also has several RV parks that will work for you, too.
If you get farther west, about 2 hours west of YNP, Dillon, Montana, has 3 RV parks that take anything from tents to Class A monsters. One is in town itself, Southside RV Park, and will put you in easy walking distance of nearly everything in town, including a small grocery store. There's also a KOA campground on the river at the edge of town; it, too, has a few spots for long rigs. The other, Countryside RV Park, is about 3 miles south of town, just off of I-15 toward Wisdom. You can see the park from the highway, but it's far enough away that you won't get road noise. The park is wide open with big mountain views and has all the usual amenities, plus easy pull-through sites.
About 20 minutes farther south, on I-15, is Clark Canyon Reservoir and Dam. On the east side of the highway is the privately-owned Armstead RV Park with places for long rigs.
As a bonus, there's also a GREAT auto/truck/whatever else you need repair shop there, too. The owner is one of those guys who will cheerfully come rescue you, fix your tow vehicle or whatever else needs fixing, and charge you a more-than-reasonable fee for doing so. We've used him regularly for work on our cars and diesel-powered tow vehicles. All over the area, he has an excellent reputation for his work.
There are free RV spots all around the entire lake, but it's dry-docking only this time of year. Water is available from pumps, if they're not frozen'; there are also toilets at each area. We live on the back side of the reservoir and have a 50-amp hookup for our RV just up the slope from our house. You're welcome to pull in and use that space, too. We have a big lake/mountain view. (Any of you MOCers are welcome to stop by and use that spot. We lived there in our Monty while our house was going up and won't be parking our rig there again for another month or so.) Shoot me a PM if you might be interested, and I'll send you specific directions to our place.
I bet by the end of the weekend, you'll have a list of RV parks for every area you asked about.
Carolyn