I just helped Steve Smith install his Duckworks HID setup; his RV-8 has the landing and taxi lights in the wingtip. Here's a photo showing how we mounted the boxes:
Note: It looks like we've got tefzel connected straight to the red cable, but that's just a trick of perspective. The wiring bundle behind the red cable comes through a snap bushing in the last rib and goes to the strobe and nav lights and such. In the photo we just haven't installed and connected the power leads that go to the red connector.
As you can see, the aluminum box is mounted to the last nose rib near the spar using the three screws and mounting ears on the edges of the box. The black plastic box is secured with a cable tie through two holes in the nose rib. I put a piece of double-sticky foam mounting tape between the black box and the rib to keep it from squirming around under the cable tie.
It was kind of tricky to find a location for the aluminum box that wasn't interfered with by the stiffening beads in the ribs. This location and orientation was one of few that didn't require any spacers between the box and the rib to clear the beads.
We discussed many different ways of mounting this stuff, including various arrangements on the spar shear web, and arrangements on a separate aluminum mounting bracket. In the end, we decided that this was the easiest and simplest, and had the major benefit of being doable with the tools and parts at hand. It also eliminated the need for any more wire holes and snap bushings, since the power leads for the landing light already came through that last rib. I imagine we'll have a look at it next annual to see how it's all faring.
Thanks, Bob K.
http://www.hpaircraft.com/hp-24 <---- now with real wings!