I've had two RV AC units 13.6 K BTU and 11K BTU which wouldn't run on 15 amp circuit. They actually would start, but the breaker would shut off after a few minutes. I have friends who had success with this however.
With that in mind, I'd say no harm in trying. Make sure there are no other loads in RV, such as Fridge electric, or the power converter. Monitor voltage and keep it over the minimum rating from the AC mfg. In general somewhere around 105 volts. Make sure none of the cord ends are overheating.
Almost no one has had trouble running just an RV AC on a 20 amp circuit.