We don't have a tv in our camper but use a Mohu Sky here at home. Its fairly small and would be easy to set up at a campsite. The mfr specs indicate a sixty mile range but we actually get decent reception on stations up to seventy five miles out with their optional amplifier (USB powered from the tv).
I checked their website this AM and it appears they now have a newer model with greater range than the Sky. Their tech dept was helpful with my questions before I made a purchase so you might want to give them a call first. Mohu - Indoor and Outdoor HDTV Antennas