howard: I haven't had to do it yet, but when I was crawling around under there during exhaust changes, gear ratio swaps, and trailer wiring installation, it looks like the battery is actually fairly easy to get to, BUT the vehicle really needs to be on a hoist to make access practical and safe.
Jim is correct, the battery is pretty accessable, it is behind the rear bumper between the exhaust pipes. It is enclosed in a metal box that opens and drops down a little bit so that you can get at the terminals. Actually a pretty nice set-up if you look at it.