I would continue to use the adapter.
IF YOU DO decide to add a 2nd A/C (And I think you should) find the wire that feeds that hole and un-hook it from the breaker box, Reolace with eithe 10 or 12ga to a 20 amp 120 volt outlet in a exterior bay.
Make a cord, 10 or 12 ga with a 15 or 20 amp plug on the male end and a 15/20 amp female end
Extend the existing A/C line to that same bay with a 20 amp plug (The neutral blade is turned 90 degrees on 20 amp plugs)
Now you can plug into 50 amps on an RV site, plug the A/C into the Outlet and it is "Factory" electrically.
ON a 30 amp site you pull the plug and use the Heavy extension cord to the 20 amp outlet in the park box (15/20 amp outlet)
With the mythical Global Warming as the world gets hotter you are gonna want another 15,000 BTUS' of cool.
