Assuming Nebraska-Omaha's attempts to join the MIAA are successful, I would be surprised if this "logical" move didn't take place:
Nebraska-Kearney to the MIAA
This would create a western division of UNK, UNO, Fort Hays State, Pittsburg State, Emporia State, and Washburn, all of which are in Nebraska and Kansas. The eastern division would consist of all Missouri schools: Missouri Southern State, Missouri Western State, Northwest Missouri State, Southwest Baptist, Truman State, and Central Missouri. The MIAA would have 12 and the RMAC 13.
Hays, KS is actually slightly further west than Kearney, NE, but UNK is in the 14-team RMAC instead of the currently 10-team MIAA.
Chadron State, while also in Nebraska, is only five to six hours from the majority of the RMAC. While Western New Mexico is farther from Chadron than the entire MIAA, most of the MIAA would be 12 to 13 hours away.