Two typical RV AC units draw enough current that by NEC it's not code allowed. Max draw from a "dedicated" device is limited to about 80% of max rated current. So on a 30A circuit your allowed 24A from dedicated devices. Max draw for many AC units is 13.5A or more so running two violates that. For that reason RV's with Two AC units on a 30A system come from the factory with a switch allowing one or the other AC unit to operate, but not both.
Now there are some newer units that draw around 11A, so in theory you'd be OK, but not much else running.
Next issue is starting current with one unit already running.
Without easy start, you'd need the breaker to handle a short term 50A load or so. Not likely happen w/o the breaker tripping
for a DIY install on a 30A unit, the easy start would definetly help. On my install with easy start, max current draw on startup is down around 20A, so the question is, with one unit running and drawing 13A, could the breaker handle a 20A several second surge? Maybe, if nothing else was on
Overall, IMHO NEC code requirements and common sense lead me to say I personally wouldn't try to run two AC units on a 30A system even with easy start. I'd convert the trailer to 50A. But then, many of the places we go are limited to 30A service, so I'd still be stuck, and when dry camping, same thing.
I just turn the AC unit on when temps hit about 74 and let it run. It will keep my trailer comfortable. If I wait till temps are in the upper 70's inside, the AC can't bring the temp down, it's able to hold a temp but not bring it down in a reasonable time.
