Jack: I cheat.

These coordinates are not intended to be "tripod holes but generally to get you close; e.g., a parking area or an intersection. I use a DeLorme mapping program on my computer, unless I have had the presence of mind to store them on the car GPS.
I did have a unit that fit on the camera hot shoe, but it sucked the juice from the battery at an alarming rate and sometimes messed with my camera electronics. In the end it was just one more piece of gear to worry about and more trouble than it was worth