On my Fleetwood 2005 Excursion 39S, there are switches over the passengers windshield and then the booster switch by the driver's elbow. The Discovery is the same. On those two, there aren't any other factory battery switches.
Bill
Nodwell RN110 out moose hunting. 4-53 Detroit, Clark 5 spd, 40" wide tracks, 10:00x20 tires, 16,000# capacity, 22,000# weight. You know the mud is getting deep when it's coming in the doors.