yep, I would say that the symptoms are indicative of the 'loose' wire syndrome, either in the GFCI main outlet itself, one of the downstream outlets, are more probably the individual BREAKER in the Main Panel... tightening the breaker's screw is the easiest to start with, without any inverter, shore, or generator power, of course.
'14 Palazzo 33.3 bunkhouse 34' diesel
KingTailgater2 Dish HD, 100w/5a SOLAR, BlueOx
100,000+mi since '14 - US, Alaska, Canada - Hiawassee, GA! (also, '14 Gulfstream Amerilite and '07 ForestRiver Rockwood) : )