I was able to borrow a stubby #30 drill bit for my angle-drill, so I drilled the remainder of the mounting holes for the remote compass mount. I had to fabricate some additional doublers for the plate, too. I then scuffed, cleaned, primed and painted the plates and stiffeners.
I also deburred, cleaned, and primed the holes in the longeron that the plate will attach to. I'm gettting used to the tight confines of the aft fuselage!
The shelf turned out to be very stong -- I'll bet it would support 50 pounds! Probably overkilll...