Is there a way to modify the nav system so that you can make changes to the destination or check waypoints while in gear. There's a sensor to detect a passenger, so can that be used to permit editing while in gear?

Welcome to the club mhallen99!

The link below shows how to bypass the swithch to watch DVD on the front screen while in motion. I am sure tha same thing will work for the NAV. It opens up on page 10.
http://www.clubarmada.com/forums/showthread.php?t=8104&page=10
If you go to page 4 theye are pics of the brake switch that you may havew to bypass to gat it to work. Good luck.

Shane aka tintmasters put up a schematic on how to wire the relays OR you could just pay him and he wold make the relays.. the mod requires removal of the radio and the relays install at two points on one of the harnesses... simple mod and works effective! it has paid for itself a hundred times over!