Add second air conditioner to 30 amp RV

Thanks for all your comments and help. My intent is to not disturb the existing RV 30A wiring system. Rather, the new A/C unit would be on a completely separate circuit wired to a plug mounted on the outside of the RV. To power the A/C, a 10awg extension cord would be run between that plug and the 5-20A outlet in the pedestal. I understood this could possibly cause the circuit breaker to pop, so I wondered if there was a better method. I am neither an engineer or an electrician, but I have experience with electrical circuits. I understand that the 50A service actually provides 2 legs of 120V (L0-L1 & L0-L2) @ 30A and this is why I asked if using the 50A pedestal outlet would be a better option than plugging into the 20A outlet. I have not been able to find a 20A EMS unit. BTW - I don't understand why manufacturers are still building larger RVs with 30A service. The additional cost must be less than $1000, and anyone who wants to install a second A/C unit is forced to jerry-rig something that should have been a straight forward modification.