Ed,

I didn't have your problem when I built my 235 but that was a long time ago
(about 1990 or so) so it's possible your panel is made differently than
mine.

That said, here's a method that might work:

Many years ago, in a different life, I had an old master machinist working
for me in the prototype shop (I believed at the time that he was so old, he
probably made fittings for Noah's ark) that was the only guy that could
drill perfectly round holes in sheet Aluminum larger than maybe 3/8 inch.
(If I tried to do it, the holes looked sort of hour-glass shaped - or
worse).

I cajoled him into letting me in on the secret and he showed me that by
drilling through a small 1 inch square patch of shop towel (the ubiquitous
red type we all use) the holes were always neat, clean and round. You just
let the material spin with the bit as you drill the hole.

Whether this will work when drilling your FG panel I can't say but then
again, it might. Worth a try.

Dan Schaefer