I would suggest matching the protector to the service that your camper will support. If your camper supports 50amp, then purchase a 50amp protector, otherwise you will be limited in the power you can draw. With electrical, you are always limited to the lowest capacity device in the circuit.
Example -- If your camper supports 50amp and the pedestal is 50amp and you have a 30amp protector -- You would be limited to drawing 30amps due to the lower capacity of the protector. With a 50amp protector in this scenario then you could use all 50amps.
If you are concerned if the pedestal only supports 30amps, then use a dogbone -- Your connection would be 30amp predestal --> dogbone --> 50amp protector --> 50amp camper == thus able to use 30amps.
Hope the above makes sense.
2013 Jayco JayFlight 26RKS
2013 Ford F150 Ecoboost FX4
2003 Coleman Bayside / 2011 Jayco Jayfeather X20E -- RIP
2012 Tacoma Sport DCSB / 2013 Tundra SR5 - RIP