Drank: We own at least two TV transmitters on all the major sites (6 sites, at least 12 transmitters) in the Central Valley from Bakersfield all the way to Sacramento along the Eastern mtn. ranges and I know the coverage in the valley very well. With the exception of the Modesto area, that 300 miles is rock solid coverage from at least one site. The Wingman isn't a "gadget" or toy. It is a passive adapter that produces UHF gain on the Batwing. The older ones you buy the Wingman as an add-on, and the newer ones are incorporated. In either case, anywhere on the valley floor from the base of the Grapevine, to well North of Sacramento has sufficient coverage that it is not needed.
BTW- there are lots of antennas better than a Batwing, but none are built for RV service.