I'd get a 50Ah LiFePo Camping battery, and wire a fused Anderson to that.
Heck
$250 at Kings Superstore will get you in the game for remote imaging.
With the cooled camera, mount, AA, and eventual dew straps, you'll probably be needing a bit of capacity.
I've found that my setup uses ~40Ah from my camping battery for a full night of imaging in just on 0c lows in the middle of winter (15hour uptime, 2600MM, dew straps, Mele3C, AM5)
I've attached a photo of the conditions (frosty!) and my little power meter reading just before turning it off in the morning.