Before I fitted the fuselage skin I had a good think about where I'm going to mount my GPS receiver. I was thinking of putting it just forward of the firewall, on a bracket under the fibreglass cowl. Many people have them mounted here with no problems, but I was thinking about clearance at the rear of the engine and decided I want to keep as much room here as possible, so I decided to mount the GPS down back, on top of the fuselage, instead.
This decision meant running some more wires through the fuselage, plus making up a doubler plate to properly support the GPS. See pictures below.
Fabricating a doubler plate to mount the GPS receiver to the fuselage skin
Match drilling my doubler plate to the fuselage surface (it goes on the inside)