Did the same thing, kind of
Yeah, after out first trip with our new Roo, we found the single deep cycle supplied by the dealer to be lacking a little (actually a lot). As we like to dry camp I quickly came up with a solution to fit 2 larger deep cycle batteries, plus a mount for the tank for the kerosene to run the Espar heater in the trailer. Oh yeah, and after I saw how much water accumulated in the battery box of the original battery, I drilled drains into the new boxes and filled the vents in the tops with urethane.
Tow Vehicle: '92 F350, Crew Cab, 4X4, Cummins 5.9 24 Valve, 6spd.Driver:Clint, Navigator:Melanie, Entertainment: 3 Boys (24,22,20) and now girlfriends too, 1 dog (Great Pyrenees/Akbash cross). Mission Statement: Just another adventure! Towed vehicle:2009 Roo 19 with lots of mods!