Just attacked this very same problem. I have a single battery in the box so there was lots of room on the inboard side to mount a Blue Sea ML-RBS 7700
remote battery switch with manual cutoff.
I have a single 2 AWG cable that runs from the positive terminal to the primary contact. Thats the only thing that comes off my (+) terminal. Off the switched terminal (of the 7700) go my Winch cable, starter cable, remote battery terminal cable, and raw power for my headlights, driving lights, and electric fans. Off the switched terminal (of the 7700) I also have a 4 AWG cable with an inline 120 amp fuse that goes through a 100 amp (normally open) relay into the terminal on a Blue Sea ST Blade Fuse Block
with 12 circuits, a negative bus bar, and a cover.
The 100 amp relay is switched by a splice to my cigarette lighter power... therefore, the entire fuse block becomes a switched power supply and only supplies power when ignition is on... ignition power is applied, which closes the 100a relay, and allows the battery to power the fuse block.
All my other relays (fans, lights, CB power) receive power from this fuse block. Since the fuse block has a negative bus bar, all circuits can ground to that, and I only have one 4 AWG tinned cable that runs from the negative bus bar to the negative terminal as well as the cable to my remote battery terminals under the hood.
It took a little figuring initially, but I like how everything is split apart, separately fused, labeled and the actual battery terminals are clutter free. Also, haven't had any problems with a bad ground since I've put it in.
Might be more complicated than you are looking at doing... you can also go the simpler route and just put in a bus bar
for your (+) connections.