if u running 30 amp, it is quiet easy to adapt the campground power to a 15 amp socket (like in ur house) and plug a tester into it (mine is yellow and has 3 lights on it) depending on what lights are lit, it will tell u if the circuit is wired correctly. that would be the min i would recommend. that tester is less than $5.
i also have an eaton surge suppressor wired into mine. cost was abt $100 once i wired it in. the suppressor *alone) was abt $70.
you can read horror stories on here abt how someone had their bacon saved by having one. i have yet to experience that.
the image above with 2 lights on is a good circuit.
the lower image, with one light, has an open ground.
actually, u could adapt 50amp down to a 15 amp plug and see if the ground, neutral, and one leg is wired correctly. if it is, u can assume the other leg is ok.