San Diego State will need some help from from the Big 12, but they could be going to the Cactus Bowl.
The Mountain West bowl scenario is more completed than most conference. First, BYU takes one of the leagues spots this year, and it likely will be the Las Vegas Bowl this year. Then there is the fact that the Mountain West bowl selection process does not go by order of finish but rather there is a bowl order and they can pick who is eligible.
As for San Diego State, they are likely not going to the Poinsettia Bowl because the Aztecs played there last year and that bowl has said that they want Boise State.