Depending on what the height of the camper is you may be better off with a small fiberglass antenna on the ladder. Thats what I run at camp (on my repeater) and it works really well. For the most part there is no metal in the camper roof. Even where the AM FM antenna is its just plywood with a ground wire on the cable. I run the Laird FG4500 and it works great. I have LMR400 run up the ladder and under the RV to the compartment with the repeater. When installed its actually a bit lower than my vent covers but i still remove depending on where I plan to drive.