You get better reception when you touch your stck antenna because your body increases the effective size of the antenna.
You could increase the size of the stick antenna by using a telescopic stick, like all cars had in the 50s and early 60s, when radio reception was more important to buyers, who had few options to bring their own audio entertainment along. There may be times when you have to collapse the antenna.
For FM, the best antenna you could fit inside a RV would likely be a horizontal 1/2 wave, drawback of that being that it is directional like your VHF TV antenna. For AM, you would have room inside the RV for a long wire. But I don't think many automotive radios have separate antenna inputs, thus they use a compromise size vertical whip for both.
That's for radio reception. But it you are thinking about satellite radio, then maybe what you want is more programming, not better reception. Broadcast radio is not what it used to be, programming usually focused to local interests, rather than entertainment programming.
For learning what is going on around me, 30-50 miles, I turn on broadcast radio. For entertainment, I bring my own music with me, CDs, flash drives, iPod. iPod can play about 2 weeks without repetition. That's a lot better than genre programming from a satellite provider with a much shorter playlist, repeating much of the program every 2-4 hours.
For satellite, I would go with a portable, rather than installation in the vehicle. That would be if I wasn't interested in doing my own programming, wanted to let someone else pick the music or talk shows for me. Even at that, I'm more inclined toward Internet radio, where the choices are spread over several providers.