Jm...I have a buddy that has a 831. If memory serves his disconnect switch is under the very front Left side(roadside) of the camper way up on the frame. That will at least kill all the power coming from the battery.
Now on our Windjammer 3006wk...when you cut the power with the battery switch and cut it back on the Gt3 appears to have no power at all....I.e. no vampire lights.
2012 Ford F350 Super Duty 4x4
2013 Windjammer 3006WK
1973 Camaro RS, LS6/475hp, 6spd