So I was thinking about this today, regarding you having problem with no one in the open spaces. I am not familiar with the map, but reading through this thread I think this might be an area where their advice on placing units could be helpful.
So I definitely identify with your need for randomness and not wanting to know where they opfor are.
To combat this though, maybe set a very complex patrol route, like 15-20 waypoints all over these areas. Do this with say 4 different fire teams in different areas. Make the waypoints sporadic and not necessarily follow a pattern. Put them all around the map in the wilderness areas too. I won't go as far to say close your eyes and start clicking, but you get the idea. Then cycle the last waypoint.
I would assume you don't play the scenario doing the same thing over and over again.
So that being said, there's no way your brain is going to be able to keep track of or extrapolate where those group are after about 10-15minutes. On one play through you might pass through an area 30 minutes into the mission and run into a one of them, but on another playthrough you might pass through that same area 50 minutes in and they won't be there.
So while you do know there are bad guys out there in a general area, you don't know specifically where they are. Which is no different than relying on modules. You know the module put bad guys in your general TAOR, but you don't know where they'll be when you happen to pass through.
Does that make sense?
In essence by using complexity and dotting their waypoints all over the map, you've effectively created randomness (by overloading your brains ability to remember or guess where they'll be), but you can fence in that randomness to the wilderness areas which is where you are struggling.
This gives you and your players something to "find" over those 2 hours, then the real fun begins as the modules really kick in with the insurgents.
P.S. I wouldn't sync those to the AI so they keep following your waypoints. If you did sync them they would get pulled into the opcom and just get funneled to the areas where the rest are (if I understand correctly)