How do you handle bad campgound power

I have a older TRC 34750 that monitors high/low voltage, open neutrals, etc. but has no display to say what the problem is when it shuts off. I plugged it in in the campground 30 amp receptacle and after the time delay it came on then shut off numerous times. I tried adjacent campsite and same problem. I am an electrician so I measured voltage hot to neutral and hot to ground and it was around 115V. Finally it stayed on and we left for supper. When we returned it was off again and it was late so I took the protector off and just plugged in. Everything in the trailer worked for about 30 min. and then there was a bang and all went black. We unplugged and spent the night on battery. We traveled the next day and when we plugged in the next night my voltage monitor wouldn't light up and the ground fault breaker in the panel would not reset even when I removed the wire from the breaker. I replaced these two items and everything else seemed OK. I will NEVER plug in again without the protector. Could have lost the TV or fridge or anything.
Brian