OK, here's some other updates...
Installed my 12v trickle charger. Will have it charge up with the 2 hour window of heating. Should be just about right to keep it topped off.
While I was at it, figured I'd attempt a hot air intake. Reused the snorkel (cutting off the little mounting tab to tuck it closer to the battery tray) and bought some 2" aluminum accordion tubing. Haven't tested it yet, but we'll find out soon enough!
Now the downside: I keep getting blink code 67 since yesterday. P0420 to be exact. We'll see what that turns out to be, but it runs fine otherwise.