Followed the suggestion to use a screen to keep them standing.
It worked like a charm.
I used screws to hold the screen up, so I could adjust it to fit the boolets.
If they touch the screen, I want it to touch above the riding surface.
These are about the shortest boolets I'm going to coat, and it worked out great.
After baking, I remover the tray and removed the screen while still hot.
I was hoping with the coating still soft, it might cover up any bare spots from touching the screen.
Looking at them, I don't see any bare spots from the screen.
Looks like another problem solved.