Did anything else 120AC powered in the coach quite? Water heater, one of the A/C's, a couple of wall outlets and such. Might be a long shot but I wonder if you might have only been powering half of the breaker box and the inverter was on the unpowered half but if that was the case you might also have lost a few other AC powered items.
Did the camp site power panel have two 30 amp outlets? If not I think the adaptor you have might not be optimum for your needs since without the second 30 amp outlet you'll only have one hot leg of the two needed for your coach.
What was your monitor reporting as volts on L2? If zero then your problem was the missing second hot.