the fuse block is located just behind the power panel under the wing. I screwed it down to the base of the drawers. I can take a photo if you would like. It's just that the wiring is a bit messy at the moment.
When I first put my dual battery in, we ran 6 b&s to the rear. I made sure I had plenty of extra wire as I didn't know which way I would end up going.
So that is run all the way to the back doors pretty much, terminated with an Anderson plug. From that I now have a "Y" cable splitter. Anderson one end, 2 the other. So then off each Anderson plug I have my fridge on one, my fuse block on the other.
Not sure about voltage drop/loss, but I figured it's better this way because everything can be dismantled easily.
The problem I have at the moment is excess 6 b&s, and my fridge cable is way to long, so everything is just kinda shoved under that side wing.
Now the fuse block I used was a Narva 6 way. These are both good and bad.
They are definitely bulky in size so that they can fit the Narva resettable 'fuses'. Not much bigger than a fuse, but is actually like a circuit breaker.
They have two positive terminals. So you can have 2 x 3 banks, if you will. Or you can join them and have 1 x 6 banks if that makes sense. This feature is a pain in the butt because I will have to make a connector of some sort.
I have a Baintech 12 way fuse block behind the passenger kick panel. It's literally half the thickness, so if you are short on space, go the baintech units.