Dual Battery Install in an 07 2720SL ?

It seems that many of the more experienced TMer's have choosen dual 6 volt, T-105 Trojans for extended reserve battery power. I trust the opinion of these folks.
But I am a bit confused as to the "best" (if there is such a thing) method to install the batteries in the rear compartment. I've read most of the threads -- including some by such noteables as Bill, Rocky Mtn Ray, Larry Loo, & Mjlaupp. Some of these posts are a few years old and I was wondering if there has been an evolution of thought on the subject. Is there any more clarity about what might be the best way to install the batteries in our particular model and should the weight be moved more to center?
Grateful for what others have already posted on the subject, Eric