I decided I should get the update and start semi-fresh. To recap, a side-loaded driver pack (I believe) prevented the update from installing. I backed up my N7 using Nexus 7 Toolkit, flashed it with 4.1.1, rebooted, got 4.1.2 OTA, then restored my apps and rooted it. I deleted my screen rotation software and now all's well. A few apps had to re-download data (including 2.4Gb of maps for TomTom Navigator), but that only took a few minutes. Note that, despite TomTom saying their app only runs on smaller resolution screens, it runs and works just fine on the N7.