Locating battery case for active mike

[JLT]

I'm building an acoustic guitar in which I'm installing an active microphone system (a Baggs Lyric). The unit came with one of those little nylon battery bags you're supposed to attach to the inside of the guitar with Velcro. Instead of using that, I'm going to build a battery case into the body. It's number 3578 on this page:

http://www.stewmac.com/Pickups_and_Elec ... y_Box.html

Do any of you other builders have a preference where to put this box? I was thinking at the base of the guitar at the tail-block, but there are two places for it: either into the rib of the guitar adjacent to the tail block, or in the back of the guitar itself. In either case, I was going to reinforce the area with an extra layer of wood to increase the thickness there to around 1/4" or so, or with some linen cloth saturated with glue. Which of these locations, and which reinforcing technique, would you prefer? This is the first guitar I've built with a battery box, and none of the books I have mentions this subject.