I do have a sense of adventure but I'm also a EE.
Go back and read your first question. Very basic electrical questions. They were on my 1st test in EL101.
My point was that if you don't know the answers you should leave this to someone who does.
With that said: the 60A convertor is 60A DC @ 12V. To convert that to input it would be 120V/12V is a factor of 10 therefore 60A/10 would be 6A feeding the convertor at 120VAC. Ignoring any power factor and consider an efficiency of 80% it might draw 7.2A. I would still use 12AWG wire.
The campsite pedestal usually have 20A/30A/50A service. Go 30A for possible future expansion. You can adapt that down to 20A with a $4 adapter.