Who is "you," Gargoyle? I've used all of those things. P-lines (preliminary lines) in the kind of forest he's walking through can just about finish you off. If you're planning a road you have to go over everything in the path along the proposed center line, often along an elevation contour, and it can be rugged. Why not suggest he run a profile from his car to his mushrooms? In my Forest Service work it meant you went straight in one direction up or down everything in the direct path of that bering until you had a clean shot from one point to another, with no ridges or such interfering with the movement of the cable that might be thousands of feet long (for a logging system).

Best for him to walk where it is easy to walk, marking landmarks as he goes, pacing it off, and if a marker is necessary, make one (as described above).

Fastest way to find where he is is to climb a tree and triangulate from there. Assuming there are any that are the suitable size for climbing (small enough). (I can't recommend a laundry cleaner for removing all of the pitch from your clothing if you do climb a tree--so climb at your own risk!)

SRS