It appears that we finally have our electrical issue resolved. Ironically it turned out to be the inverter that Forest River had swapped out on a recall shortly after we purchased our unit. The inverter was bad and was overcharging the house batteries and then causing a draw when the unit was not on shore power or running. It appears, and appears is the operative word here, that the issue is now resolved. It did, however, require me to purchase a new inverter and also replace my house batteries again.
2011 Berkshire 390bh