When buying surge guards there are two ways to go.
1: If you have a 30 amp trailer get a 30 amp protector, if you have a 50, get a 50, Do not worry about the park's outlet, get a dogbone so you can plug in anyway (For example just now I'm in a 50 amp rig on a 30 amp site with dogbone adapter)
The other school is this: If you have a 30 amp rig get a 50 amp and a pair of dogbones (one each way) that way when you upgrade to a 50 amp rig you are good.
Frankly.. i'd get the 30
When you are on a 50 amp only site or a site with a bad 30 but a good 50...
Park--Dogbone adapter--EMS--RV
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times