The false bulkhead - trough area is a danger zone!
#1. Clean under the fuse box and master cylinder.
There is a resistor in the trough under the brake master cylinder.
This resistor gets hot enough to set fire to leaf and mulch that gathers around it, ask mplafleur how serious this is!!!
#2. Clean under the battery tray.
The following picture is typical for what I find when the battery tray is removed.
The picture is a W126 1987 California 300SDL
with optional Rodent nest.
This owner was lucky; the mice chewed the sheath but not any wires.