I am not familiar with the area either and also agree with a wide net via inquiring about anybody who has seen or heard something anything no matter how small.So, when I do experiments, write proofs, or test data, I try to keep as open a net as possible. Again, I am not familiar with this area. So, from the outside looking in, I would look for any backpackers/campers of any age...
The area is a forest, not a park. So, other users in a broad net approach could include: ATV types, target shooters, partyers, ranchers etc.
it might be good to have "broad net" question and a scenario driven approach at the same time. For example:
- Broad net: Did users 'D' and 'U' see or hear any thing no matter how small?
- Scenario driven approaches could include:
"Trespass Punisher": Has a camper started to "claim" a part of the forest? Is there a leasing rancher known to lock public gates or approach people and claim that public access is forbidden etc.
Sex Stalker: Are there any specific back packers or others known to have harassed females, shown in inordinate interest in couples via following them, trying to strike up conversations etc.?
Freedom fanatics: Have certain target shooters or off roaders received complaints in the past that their fun was endangering others? Or, did they seem to deliberately "amp up" their fun to harass other users?
Hunters and fishers with bad 'tudes: Not hunting season and area does not seem to be prime hunting location, so hunters with 'tudes may diminish.
Fishing 'tudes could include: Any fishermen in the past known to aggressively approach others about real or imagined fishing faux pas? Any fisherman known to have wasted fish, fished with illegal methods, blatantly taken restricted species, had "claimed" a certain spot etc?