The fuse for the mirrors will likely be in the grouping of "chassis" related items like the fuel pump, headlights, turn signals, power steps and such -- and not with the 'house' loads like the internal light fixtures, etc.
There were many fuse blocks on my coach, but the chassis related ones were in the basement compartment under the driver's window or under the dash...
Of course, it could still be a loose connection or a burned wire in the harness...either of which will be a lot harder to locate.
2007 Tour Master T40C
Acura MDX toad
"It takes a great deal of time to recover from any improvement..."