Finally got some time to spend on attaching feet. Initially I picked out some screws and was about to drill some pilot holes, and backed out of that. Didn't want to disturb the bottom in case I changed my mind later, so I went with a strong tape. But that would require the insides to be filled with something so there is a surface. I started by grinding down the middle piece, which was a bit too high and had four little nubs sticking out of it. Then I drilled some holes in the support fins to allow the material I add to stay put.
I found some quick set putty that's sandable in 60 minutes. It set so fast I had to buy a third tube of it because the last chunk got too hard after only 4-5 minutes. I was just a little short on two feet so I had to rough them up a bit and fill it out with a little more before sanding. Hard as a rock though, worked great! Then I cut the Gorilla tape using the cutting machine, using sticker backing paper destined for the trash.
I first chose rubber cement to glue the Gorilla tape to the feet, but thought I might do better with some silicone. Bzzzt wrong answer! The tape peeled off the foot before the backing would budge. So I went with some E6000, that worked. I roughed up the tape surface a bit too, so that probably helped.
Kept them under a little pressure to set (the tape edges were coming up) and stuckem' down! I got the front two a little off so I had a chance to find out how well they stick by taking them back off for a re-center. They're not going anywhere
One silver lining: I initially figured I'd place the front ones farther forward, but didn't think that doing so would make removal of the front panel impossible without taking the feet off first. But, the way the tape didn't quite fill the bottom, I used that little slice that didn't get covered with tape to stick out past the ridge, since it had no glue and had enough clearance to get over the start of the front panel. Just enough that there's still enough of the foot taped down.