Thanks all.
I currently have my solar bypassing the master battery switch. If I include the solar in the master switch, I could dedicate the solar charging system to the external battery via pigtail when the master battery switch is off. Therefore, not affect the house batts. I would lose the refrigerator, small inverter and parasites for those few hours. 1 quart of ice would compensate in the refrigerator. Or, I could add an additional switch to temporarily cut solar to the house batts but still power the pigtail. Might confuse the Trimetric either way.
Time to buy a digital amp meter to check the ways.