Although it wouldn't be as good of an institutional fit, the Great Lakes Valley Conference is losing SIU-Edwardsville to Division I, so Central State should move in as the 14th school once the Cougars leave. Even if NKU leaves, Central State is close enough to Indianapolis (about 2 hours, 15 minutes) to be geographically cohesive.
There are also quite a few road trips in the SIAC that are longer than all of the road trips Central State would have as a member of the GLVC, such as Paine (Augusta, GA - 10 hours), Stillman (Tuscaloosa, AL - 9 hours), and Tuskegee (10 hours), and Fort Valley State (10 hours).
I agree, those road trips are a pain for a school just restarting it's athletic program. The GLVC (or even GLIAC to replace the departing Erie schools) would be a better fit for them than the SIAC.