Unanswered questions at this point are how best to switch between solar and alternator charging, and whether the battery box will ever leave the car.
For the first part, right now it's just going to be yanking the plug out of the battery feed and swapping in the panel. Simple and probably effective enough but I'd kinda like a big solar on/off switch somewhere. Maybe.
Everything is simpler if the battery stays in the car but maybe it's too inflexible. I'm about 50/50 on this issue.
Minor note about my wiring here - the most cost effective way I found to get all the cabling was to buy some discounted, shitty jumper cables and cut them up. I have hidden many sins under heat shrink wrap but hey, it works!
The battery percentage is going up while I'm using it, so that's a pretty positive sign.
@mike That's a gorgeous laptop btw.