I use the GodSam GPS. When we decide we are ready to call it quits for the day, we search RV campgrounds on our route. It comes back sorted by milage and we decide how much further we want to go. Usually call campground and make sure they have room and proper facilities (like a drive thru spot for overnight stay).
Works absolutely great.
We have been here for last week -leaving Saturday early. Beautiful time of year. Just be advised the leaves are turning and the crowds are getting crazy. Traffic is a zoo in Gatlinburg. I suggest finding a spot in Pigeon Forge. Saturday supposed to turn cold - 20's Saturday night. Enjoy your stay.