Thanks again for all the helpful replies. I ended up going to Sams Club and purchasing a pair of GC2 6 volt golf cart batteries for $85 each. I might be able to squeeze them in without removing the slide-out battery tray, but if I have to remove it, I will.
To charge the batteries while driving, I have a 10 gauge wire from the truck battery to the RV battery, with a 200 amp rated switch. I close the switch when the engine is running, and open it when I camp for more than a day, to make sure I don't drain the truck battery. Also, there is a pair of 10 gauge ground wires from the RV to the negative battery post on the truck. This seems to do a good job of keeping the batteries up when I drive all day, but short trips don't accomplish anything.
I also ordered a kit with a pair of 200 watt flex solar panels off ebay, and a controller. They were on a black Friday sale for $386. I wanted to get the flat flex panels because they are lighter, and because I can glue them down, thus avoiding holes in the roof. My Arctic Fox TC is supposed to be pre-wired for solar, but I don't know what size wire they used. The wire from the panels to the controller will be short, 6 - 10 feet.
.
Here is the solar panel kit: http://www.ebay.com/itm/231747724588?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
I will let you know how the installation goes and how they work out. I probably won't put them to a good test until February.
