What I did (note: actually did) was install a 30A receptacle for my RV, and a switch inside the garage dedicated to it. There are readily-available heavy-duty light switches rated for 30A, though normal light switches are not.
Since the RV box would not be the same circuit as the house A/C, you need to run separate wires for it anyhow from the electric panel, so I don't see where you're really saving much by combining the two jobs, at least in terms of materials. It may well be some savings in labor to do both at the same time.
