You don't need a 50 amp service, or even one leg of the 50 amp to run one a/c
Remove the a/c circuit from the breaker in the panel
Get a small double breaker box, but in a 20 amp c.f., Conner the a/c to that
Run a new cord circuit 12 gauge from box to o outside with a 15 or 20 amp duplex make plug on the end
A single 20 circuit from the power pole is all you need for the air
And this will work every where
Not all camp grounds have 50 plugs
Do that or change the th over to 50 amp service with new breaker panel and new 50 amp cord