Step 1: Buy suction cups
They are rated to carry 3 lbs. each.
Make sure you examine them carefully. I had to return one that was not sticking to the glass because it was a bit distorted.
Remove suction cup from clip. Save clip for other uses.
Step 2: Mount support strip
You could also use a piece of 1"x1" wood or other material.
Drill holes for the suction cup screws at each end of the support strip.
Also drill a 1/4" hole for the camera mount screw in the center of the strip, but perpendicular to the suction cup screw holes.
In my case, the screws that came with the suction cup were fairly short so they worked with the thin aluminum.
If you use wood or thicker material, use longer screws.
Just make sure the screws don't penetrate the back inside surface of the suction cup.
I had to use washers to make up the required thickness to ensure the screws did go through the suction cup.
Step 3: Camera mount
This takes a standard 1/4" -20 thread screw.
Again, use washers if your screw is too long for the condition.