You all are talking about a Trail-Lite, but I posted in the "C" forum a couple of days ago about a similar battery issue. I have a BT Cruiser 23 footer and installed two batteries and am now going to three! I got various opinions about doing this, and finally emailed Gulfstream and their head electrical engineer emailed me back in about two working hours with the answers to my questions about three batteries.
We, too, boondock most of the time and wanted more juice. I am going to put three Series 27 batteries on board and increase whereby we can spend several days without recharging.
When we first got the BT Cruiser, I immediately added another battery for boondocking. It is really a neat thing to have two coach batteries. I encourage you to figure out where to hang that baby, because out in the boonies, you will really love not having to fire up the generator.
PSW