I just got back in from finishing its installation:
It is wired directly (fused, of course) to only the second battery. When it is on and doing nothing, the LED there pulls 68 mA. I think it would be useful to have a 12V plug and USB charger that didn’t risk the starting battery.
Also, it seems like the camera on my phone is getting worse. I may have to switch to some old telephone to use for photos. I think I have my Sprint Galaxy SII kicking around somewhere. But, that notwithstanding, I also installed all but one of the panels:
The remaining panel is the one in front of the driver’s side rear wheel rocker area, as I have to cut that panel out and weld the new one in, so there’s no reason to install the plastic just yet. Welding will probably be done next week, unless it rains again.