I used a Paradise conversion plate as a top mount on a 3/4" wooden panel awhile back. Don't know if this info. Is helpful or not. I traced it and routed to even depth and installed. I then installed the stick connecting bolts with jb-weld and screwed each one from the other side with those tee nuts (think that's what they're called) and let everything set. I then ground the pan screw heads even and applied a coat of bondo to fill and installed artwork so no lines visible. I know you're using a metal panel but maybe some of this would be applicable to your situation.
for future reference, you may be able to contact a metal fabrication shop, who for a few bucks, can use a type of spot welder to fuse a threaded stud onto sheet steel often called "stud welding". call up a couple places and ask if they do such a thing, and if they do... if they have some time to install 4 or 8 (or however many you need) studs onto your sheetmetal. if you aren't picky about how long it could take, you can get a great deal (sometimes a buck or two a piece) but if you have a schedule you need to keep or need it immediately, be prepared to pay shop rate plus the stud cost.
there is no penetration through the metal at all since the stud fuzes to the metal and will remain in place fairly strongly. i have managed to tighten one down hard enough to break it off, but i was being really overzealous with it... and i had a couple on one panel that didn't quite fuse on there properly and they broke off easily. (i think there may have been some residue on the metal preventing proper fusing.) both times the shop just rewelded new ones on there while i waited, no questions asked.
overall they are a great way to mount stuff to your metal panel without making a bunch of holes you need to cover or fill... which is great for a painted panel.