The obvious answer, and in keeping with Theodore Roosevelt's axiom, "Do what you can, with what you have, where you are", arm the MAs and USMC MPs at the NOSCs. They are trained and know how they fit in with civ law enforcement. In cases of non-specific elevated threats due to things such as key holidays or anniversaries, pony up some extra drill pay and send those guys to the NRSs that could use extra security.
That assumes you have any Full-Time MAs or MPs. I'm actually curious if there are any MAs in the FTS world. Sending guys on drills to go get qual'ed seems to be a good use of their time at first, but then they're not actually around during a normal workweek since they're not Full Time. It certainly doesn't hurt anything, though.
What I find interesting was how someone did exactly what you're saying...made do with the conditions at hand and decided to violate DoD directives. I'm sure LCDR White will get his peepee smacked, but it's hard to argue with his actions when it turns out his actions potentially shortened the altercation.