So last year I upgraded all the batteries, and installed a solenoid to keep the rear batteries separate when not charging, and moved all of my aftermarket electronics to the rear bank (stereo and lights, etc)
I never really put it to a good test last year..so last night I went to my brother's house and he wanted me to park by the fire and play music, great!
I had the toons cranking, bass going, and 1 set of neons running for almost 4 hours straight, rear batteries were still holding up nicely, and as I was planning, the front battery was 100%. No issues starting at all.
I need to set it up and just let it play music till it dies to see how long that will last.