DUDE!
Your wife/gal must work a couple cities away... or you are REALLY bored. This one oughta go in the archives.
Great tech info.

[EDIT: is this the Brian who is currently enduring my son, BTW??? He really really looks up to you, FYI. He's having a great learning experience.]

I plan on mimicking Roger's setup electrically in any event. That means, I will run TWO positives up front to the engine compartment/winch, keeping the two circuits separate so that the aux batt runs the winch and accessories, the primary batt runs the engine etc., and a solenoid (when active) parallels the two circuits (allowing the charge circuit to charge both batts when ignition is on, but isolating the batts when its off, but both batts are available for their respective duties).

This puts only the charge current and perhaps some equalization current through the solenoid, and in a large draw situation will allow more current but never more than 1/2 or so of total depending on relative battery condition and the current will pass through each battery's positive instead of just one positive cable.

The other alternative, putting the solenoid in the rear with the batteries (actually does not matter *where* the solenoid is, the key is one, or two, cables running forward of course), would route all aux current through the solenoid in the event of a large draw (or any draw, though still probably not more than 1/2 or so) and provide only one positive in the engine bay via one positive cable. Because of this, the main batt would be the only available one with the ignition off under this approach.

Good advice on armoring the positives. I will have to compare some good split loom armor vs. heater hose. Not sure I want to go with the fusible link, but I might.