Update: I was able to get the rt2x00_usb driver to work[1][2]. I ended up simply forcing a call to unblock_time_handler() before ever running the linux scheduler. The driver can associate to networks (at least mine) and serve the test page when run under the test scenario, and it can download the "sticks blue background" under Sculpt. However:
1) It's very slow, noticeably annoying, and much slower than ath9k. I'm not sure the best way to try to diagnose this.
2) It does not recover with an rfkill unblock following an rfkill block, so after an rfkill block it stays offline.
3) I haven't tested physical plug/unplug cycles under Sculpt yet.
Josef I am curious if this version will also work for you?