Well, having intended to use only aluminum - I took my perfectly fitting template to a professional shop to have it cut out. Turns out, they couldn't/wouldn't simply trace and cut. All seemed OK dealing with them - long story short, they cut a test piece out of wood, I pointed out the problem, they said OK, I went back when the aluminum was cut - took it home, and they had not addressed the problem. They made the same mistake I made in the first place which caused me to seek a professional. The bottom line is not straight
So, it didn't fit - was out a 1/4 of an inch if I ignored the gap, and there was no way to reshape it to use it.
So, I returned to my thought of using plastic - much easier to work with - but not as strong, and how to attach? Well, I went to the plastic shop - of course, can't use my template, take too much time, etc etc. So, I bought a rectangle piece of 3/16" ABS and took it home. I was able to shape it to match my template exactly. And, I figured in that process that I could still salvage the aluminum effort as well. I ground it down to reshape it, and use it as a back piece - strength, support, and better for mounting.
Also, the aluminum piece worked great as a template for cutting the holes.
Got the holes cut in the ABS (holy pain in the neck to deal with - stuff melts more than it cuts/drills) - but it shapes and files with ease. Really good for working the gas door on there.
Used some 3M spray adhesive to fix the 2 pieces together. And hit both sides with a scotch brite pad - aluminum just to clean the backside up, and the plastic to help the paint adhere.
Then drilled the rest of the mounting holes for the lights.
Here's some pics - not done yet - I will apply final paint to the panel and wire/assemble once the chrome trim rings I have ordered arrive.
