I am a CO, and former Army guy who has spent more days at military " role playing training facilities" than I care to remember, although never at one specifically for SOCOM.
The key here is that the requirement is for a large training area, enough for 4 village sites and a road network, "within 15-mile radius of Camp Mackall."
How many such areas could possibly exist? My guess is - one. There is only one possible location.
Everyone in the know knows exactly where it is, who owns it, what their price is, and what can or cannot be done on it, and how. If you have any chance at getting this contract you either own that land, or are best friends with whomever does own it. Given that fact, SOCOM probably felt no need to go into further detail in the solicitation.