I ended up with a pile of crap that I later cleaned up and sprayed some gray Krylon onto.
The mirror heads (Truck-Lite 97646) came from here @ $11 each:
http://www.truckpartswarehouseonline.../TRU97646.html
I still need to see what happens when I remove the first nut on the mirror head studs. It was already late/dark when I was putting them on, so I just spun one of the brackets around for the time being.
I think they look pretty good...