CGI, MWA, PAH,and OWB are close enough to share mechanics or help each other in a tough situation.
And they are close enough to Whistle-stop should the need arise.
Having Contour in all the stations nearby would certainly help with the IRROPS, but they all fly to different destinations so the whistle stop I don't think would help too much?
I suppose if needed Contour could fly MWA-IRK-ORD, and PAH-OWB-CLT to help out.
Funny enough, some social media page on Facebook NOT affiliated with the MWA Airport, posted the wrong image stating that Contour is flying MWA-STL/BNA, same as Cape Air, so everyone is voting Southern because it's Chicago, not realizing Contour is also offering Chicago as an option. I have repeatedly messaged the page to try and correct it. *sighs*
If Cape is selected, they operate at the end of L for now. EAS parking moves in March over to T5.
If Southern is selected, UA will add them over on F as they currently are located for parking. Counters and bag makeup will be at the end of Terminal 3 where they are currently.
If Contour is selected, there's two options; one is being accommodated by American and the other will be T5.
For MWA/IRK/OWB Cape Air was not offering Chicago, only STL or/and BNA.
Now with Cape Air losing BRL and UIN, the only Chicago route Cape Air will serve is from Manistee.
Selecting Contour would be a drawback for connecting to American with the interline, Southern would be great at ORD for utilizing F4 as you said.
I am biased, I live in Chicago and from the Marion area, I would go with Contour or Southern but that's me.
The question is, does choosing Southern require them to waive the multi engine, even though a Saab 340 is flying the route to ORD...