In my case, however, there was absolutely no possibility of locating the battery bank further back. It was either under the V-berth, or back with the other house batteries in the aft end of the boat.
Also, I have no intention of installing a washdown pump or a bow thruster or whatever. I already have a searchlight: it doesn't draw much current at all and runs from the ships 12V wiring system via any outlet on the boat. Ditto on a washdown pump: minimum amperage draw.
One other concern these days: the price of copper wire has skyrocketed. I can't imagine how much a 60- or 70-foot run of 4/0 or larger marine cable would cost. Together with the cost of an additional breaker or fuse setup...you'd need one at each end of this humongous cable....you'd be looking at a lot of bucks.
Even further, charging would be a bit dicey, since even with a 4/0 cable the forward batteries wouldn't be at the same potential as the main house battery bank. It would probably be best to install an EchoCharge...another $100 or so. Or a combiner. Or a huge switch with a combiner/echocharge, etc. Not good solutions, to my mind.
Nope, for me the completely separate forward battery bank works, both in theory and in practice. Admitedly it ain't for everybody.
BTW, this battery stuff is a problem. Just ran into a friend at the marina who was trying to help out a buddy on a new-to-him 46-footer. Seems the yard looking after this boat had left the inverter on with no AC to the boat over a period of several months. The load was refrigeration and a few other things. Predictable result: a bunch of very dead 4-Ds! Ouch.
Cheers to all. It's almost time to get out there on the water again (I believe the last below-freezing night in the Chesapeake region was last night).