Hmmm, not sure about the nature trekker. I have the stealth backpack from Lowepro, and the LE fits in there with the standards parallel to the rail with no problems. In fact I have the camera in the main compartment along with two lenses, the bellows, dark cloth and polaroid holder in the other big compartment, and 5 holders in the largest outside pocket. There is an additional small pocket that holds my Pentax meter, cable releases, etc. The Nature trekker may be a little too narrow to be able to hold the camera with its standards on the rail. I'll look at one of them tomorrow at the store and see if I can come up with some sort of brialliant plan...
Isaac