Anyone install an accessory battery?

I'm considering installing a LiFePO4 battery somewhere in the car. I was looking for an ultra slim battery for under the seat, but then I realized the foam compartment in the back is sure taking up a lot of room. Curious if anyone's done something like this in the Gen 5.

 

Ok so here is my current idea:
$205 | Victron Energy Orion IP67 24/12-Volt 100 amp DC-DC Converter, Non-Isolated
$699.99 | Renogy REGO - 12.8V 104Ah Super Slim Lithium Iron Phosphate Battery

I overestimated the depth of the foam in the LE model with, so sticking with an ultra slim battery. It looks like I'd be able to cut away a slot in the foam to get it to fit snug. With this, I'd be able to keep a dashcam powered on for over a week if I needed, but I'm also thinking about the utility when it comes to camping, charging stuff while I'm away from the car, etc.

 

Oh good catch. I thought it meant it uses either 24 or 12 volts.

The Renogy battery I linked says it recommends at least a 50a charger, so this would be better:
Victron Energy Orion XS Smart DC to DC Battery Charger 12/12 50A (700W)