I wound up using @Venson’s design—see 15mm SSD Mounting Bracket? - #15 by geerlingguy
That, plus a $28.88 DiliVing SlimSAS to U.2 cable (Amazon link: https://amzn.to/3QuD6B2), seems to get me two working drives.
Power was a little sketchy—I didn’t have a molex power splitter, so I just yanked one from the power midplane and connected it to the molex 4-pin power input on that DiliVing cable.
I ordered a StarTech.com molex Y-splitter and will use that once it arrives. Shouldn’t be an issue as I don’t think the midplane routes each 4-pin connection to individual pins on its backplane power cable. I think they’re all in parallel?