On CO/NW this is one of the flaws in the system, fortunately for me, I am able to use this to my advantage most of the time since I don't fly out of a hub city at either end of my itin.
I'm not sure there is a way to beat the current system. Now if you are flying as a companion upgrade on CO/NW, I don't believe there is a way to beat the system. If you are a CO/NW gold, then you should hope that your EUA runs the night before or at the 3 hour window, if not THEN check in as a companion (hopefully with a Plat) b/c then you will be listed as a plat and go ahead of the golds and silvers. If you really want the u/g then use miles or pay.. those would be your only other choices that I know of