I screwed up by having a 12 x 30 ft steel cover put up. I had a 24 ft Class C
at the time with no slides. After a yr or so we wanted something bigger, bought a 34 ft 5th w with slide. then I had the length extended by 10 ft, had to raise the top by 2 ft. I still cannot hardly park the RV since I have to have the drivers side 2 to 3 inches from the side of the cover in order to open the door to the RV as it has extra wide door.
Make sure you have it wide enough in order to stay in it in emergency. Wide enough to open the slides, tall enough in case you buy a bigger, taller RV