Make sure your 30 to 50 dogbone passes power to BOTH legs of your 50amp feed - many coaches have one AC unit on one leg, and the other on the other. You need to make sure both legs are getting power. I'd test it before you get there to make sure.
And if you're lucky enough to have an energy management system that keeps track of your current draw, set it to 30 amps and it'll shed load as necessary to keep you under 30amps. On our coach (although it's a 30amp coach) the rear air automatically shuts off when the microwave goes on, and then comes back on when the microwave's been off for 30 seconds. Wouldn't have a coach without it.
al