I think it could be done in next way:
Base member(s) travel on WM, someone other with higher outdorsman and perception cross them, and he will have option: "follow wastelander group". The higher skill, the longer he could follow them. When base member enter some location (base, or other enc), this outdorsman guy will see this location until death, until he enter other location, or log off.
I think each percent difference in outdorsman will allow follow for 1 second. So with 200 outdorsman, it will be possible to follow for 2 minutes if base member have 60% skill.
It is not possible to send radio signal to show base. But This fllower could bring merks/other people for raiding.