If the RV is fiberglass and has a ladder, you can use the ladder as an antenna. This idea was written up in the ARRL Antenna Compendium number 7.
As for you current installation, the ground lead is as important as the lead to the antenna. You should replace it with flat braid.
Any vertical antenna needs a groundplane to work against. Whether this is radials, a metal body or frame. That is to say, to act as the second half of the antenna. If at all possible, the whip should be mounted directly on the frame (insulated from it obviously), or frame extension. In other words, not on fiberglass!
Lastly, the antenna should be made longer if possible. While 8 feet works, 12 feet will work MUCH better. If you look over my web site under Antennas and under Auto-Couplers, you'll see what I did and perhaps it will help you.