I have good ventilation in the front cargo bay of the 5er, so I break all the rules about putting things near batteries. Got away with it so far (a few years or so)
On the "load side" of the shunt, I have a length of copper pipe which takes any clamps I might use from portable chargers. Also for the neg wires from any solar controller(s) I am using in the 5er. (I now have clamps on my controller output wires, which I mount in a portable sort of way to swap between 5er and TC.)
I recently flattened part of that copper pipe and drilled a hole in it to bolt more neg wire lugs that don't go on the inverter neg terminal "buss."
Here is a photo of my set-up a couple of years ago, which has since changed somewhat, but you get the idea.