After a bunch of thought yesterday and today about how to support the tubes and wires going through the center tunnel, I set about making a couple brackets with which to fasten some Adel clamps. These two brackets are 1 5/8 wide x 5/16 high and about 7 3/4 wide. I made them with the little 12" Di-Acro brake.

I also fabricated these little 9/32 thick spacer blocks from a chunk of 3/8 thick 6061-T6 alum.

After drilling out a few rivets on the bottom skin and transferring the holes through these brackets and spacers, this is how they're going to look. The Adel clamps will screw directly to these brackets.

I drilled and dimpled for a half dozen nutplates on each bracket. Three will be used for tubing (one fuel line and two brake lines), so that'll leave three more for whatever else needs to be run through here. Hopefully there will be enough space under the tubing and wiring to install some insulation.