The grounding for the RV trailers is done back at the source. There is no need to add a ground rod at the trailer...
This is a typical campground pedestal wiring configuration for the 50AMP and 30AMP connections...

Notice the EARTH ground connection back at the source shown in GREEN...
If you are melting shore power cables then you must not be using large enough wire size... We are connected to our garage 20AMP SERVICE at home using a 50-foot 10 GAUGE (10-3) contractor grade HD extension cord and using a RV30A-15A long adapter (WALMART) laying in the middle of the back yard where our 30AMP Shore Power Cable is plugged into the long extension cord. We run everything inside the trailer just fine. We do have to watch what is on at the same time like if the Air COnditioner is running and we fire up the hifh wattage microwave it will trip the 20AMP breaker in the garage...
My cable connections are all cool to touch...
Roy Ken