I don't think your average spam-can driver is willing to spend the time to get a ham license (or get a field approval for a dedicated APRS tracker). RV builders, being true experimentalists and DIY types, are a different breed. Its ground-based hams that are the real concern, and people should give some serious thought to whether they really need to blast a signal out at 8 watts if 3/10 watt gets you what you need. That will do a lot to ease congestion.
Rich in Denver just completed his first flight in the metro area, had the dipole taped to the canopy and enjoyed nearly perfect tracking on 300mw (are we in the process of putting the "congestion problem" to bed?).