re: Boise to Big 12-3+1 makes the most sense.

I think you're implying that they want that, or that that's advantageous to them somehow - it just isn't, especially with seemingly large-scale changes to the way the postseason works and conferences work imminent. They don't want it, their fans don't seem to want it, and I think it would be good for football generally to try to get them into a major conference, if for no other reason than to raise the level of competition for both them and other teams.