Sounds like you got a pretty good answer... Let me throw my two cents in anyway...

http://www.xterraownersclub.com/cgi-local/ultimatebb.cgi?ubb=get_topic;f=38;t=001174#000000

Mounted the tuner under the passenger seat, and it has never been bothered. Wires went down around inside of hatch door, and through the eyelets of the taillight into the cabin, under the carpet, and to tuner...