All done ...
Since there's no posts detailing an install of a dashcam with a battery pack, here's what I did:
You can see the grounding post I used on the left. On the right, I tapped fuse 162, which is a 20A ATO fuse used for the rear 12V accessory socket (which my car doesn't have anyway). It is a switched fuse and because the battery pack draws 7A for charging, a minimum 15A circuit is recommended which is why I used the 20A.
As well, I tested the direction of the fuse tap for the proper orientation and the arrow shows the side to which the fuse tap tail should be sticking out of.
I chose the Cellink Battery B because I didn't want to spend the extra cash on the new Blackvue B124 or the Cellink NEO and the older B112 has pretty crappy reliability from everything I've read. The B should do for my needs nicely.
Here's the Battery B installed:
I have just a bit of cleanup to do with the wire, but I put it there because I do want access to the power switch and the indicator lights without having to pull up the trunk floor panel.
The camera I chose was the Blackvue DR590W-1CH and I spent the extra $$ on a Blendmount for it as I didn't want to stick the mount to the windshield (not exactly stealth and I drive to Washington and Oregon enough that if I get pulled over I wouldn't want the extra ticket). Ran the wire across the headliner (nicely tucked in), down the A-Pillar behind the weatherstripping, and under the door sill to the rear seat where I tucked it in and brought it through to the trunk.
If anyone's interested in pics of the cam or the mount, I can post up.
I can post up picks of the camera install if anyone's interested.