Thank you to everyone for the tips. I will unplug the alarm and PSE pump to see if that makes a measurable difference in the drain.
I should add that I installed a 150a alternator from an R230 and added a 4awg wire from the alternator to the + post on the driver's side inner fender so at least my charging system can deal with afterglow and bring the battery back up quicker than stock. We're taking the car up to Tahoe this weekend so it'll see a few cold starts below freezing. Living dangerously.
