if the pedestal that you plug into has a 50 amp receptacle along with the 30, you can do what I did.
first find out what is feeding your pedestal. If it is a 100 amp and wired for that, you are good to go.
I installed a 100 amp panel in one of my compartments. Then I changed the 100 amp main breaker out to a 50 amp one. I installed a new cable port and bought a 50 amp extension one. I cut the female plug off and used that end to connect to the new panel.
Now I have both a 30 amp, 120 volt supply and a 50 amp, 220 volt one. You can connect your new A/C unit to a 20 amp single pole breaker on the new panel and have plenty of extra capacity for a washer and dryer or what ever else you want.
You can only do this if you own the power pole and are paying the electric bill like I am.
jack L