When measuring to pick out an RV storage cover you need to measure the box length. What that means is not including propane tanks, ladder, coupler, AC units, or trailer jacks. Just the "box" portion of the camper would be all that you'd need.
If you let me know what camper you have I can see what would work best but the part # 052963731637 that you referenced would fit from 17-20 foot campers. view full answer...