take 287 from Denver up to I 80 and go west to Rock Springs and take 191 north.
There is a gov. campground about 20 miles north and west of Pinedale, on the Green River, quiet and cheap and has water and a dump station..if you are wanting to stop. An easy drive into Jackson from there.
In Jackson, there is the Virginian RV park, very nice, but a little pricey for us, and we always go through Jackson and north into the Park and then east to Gros Ventre campground, a park campground with water and dump. they have elec sites, full hookups, but they run about $40 night. you can't reserve these but the campground hardly ever fills, and if you get there by 10 or 11 a.m. there will be some sites available.
Or you could do both. Stay in the town one or two nights, then move out to the park campground.