Ordered my aluminum today from onlinemetals. Should be here Tuesday, hopefully I can get everything done by the weekend of the 15th when I have a big wheeling trip with a night run!

I measured the factory mounting points to be 8" apart, and 31" from one side to the other. This, along with the available aluminum stock sizes and type of load we're looking at, dictated the design. I then maximixed the distance between lights (came to 7.25", so this is good for a 6" light) while allowing access to the retaining pin. For the pin, I'm going with McMaster part no. 95255A275, it's 1/4" with a 2.3" usable length, a perfect fit for the 2.25" tube!

I finalized it today during lunch, ended up ordering a 29" round tube cut to size for the actual mounting bar. I'm going to machine all the holes in the round bars/tube, and then I'll be match-drilling the mounting holes on the angles that will attach it to the factory rack, based on how everything fits.

Here's what it looks like: