All,
Auxiliary Battery wiring upgrade: Having completed a fair amount of research
I am attempting to answer my own question about best practices and the use
of the aux battery.
1.      run #6 wire from the main to the auxiliary battery for the + leg
only. Drill holes on bottom side of both battery boxes and run wire over top
of gas tank, add in rubber grommets and run flexible plastic tubing to
protect new wire, caulk tubing into place with silicon??
2.      Fuse #6 awg wire at aux battery side with a 60 amp inline fuse. This
should handle any high temperature conditions that the interconnecting
battery wire may see.
3.      Ground aux battery at spare threaded ground point in compartment
under driver seat (high on right (passenger side) of battery box)
4.      Try to reuse existing GoWesty Auxiliary Battery Kit and existing
Second Battery Relay 411-915-511B. Upgrade wiring to carry #6 through relay
and isolator. If this does not work look at using the Blue Seas isolator
controller and battery switch instead.
5.      Use Blue Seas low voltage subpanel with integral ground to control
interior power, stereo, lights, fridge, sink pump etc.

I think that this should cover all contingencies as well as be properly
fused to handle any potential overcurrent or ground conditions.

It would be great if I could get some feedback on my plans.

Kevin