As absurd as it sounds, could a "double" train be put together to run MSP-CHI-KCY or MSP-CHI-Cleveland to avert the "local" train issue? I'd be thinking what amounts to merging another desired rout with this one...regrettably, MSP-CHI-Cincinnati is 12 miles short of the cutoff, MSP-CHI-Detroit is 34 miles short, and MSP-CHI-STL is 31 short (in the case of Cincinnati, the answer might just be to route the train slightly "off" to push it to 751 miles with some sort of slightly inefficient track selection; in the case of Detroit, routing through Toledo would solve the problem). You might make a hash of the timetables here, but a full crew swap in CHI (if not an extended layover of some kind) would solve most associated issues...organize it as one route but treat it as two that happen to exchange trains.
Edit: Actually, I think the KCY-CHI-MSP bundle would work well: 304 leaves KCY at 8:15 AM, gets into STL at 1:55 PM. 314 leaves STL at 3:00 PM, gets into Chicago at 8:40 PM. Join the equipment, back 304's STL departure up somewhat (move 314 by 15 minutes if you need to), and have "324" leave CHI at 9:00 PM for MSP. Coming back, get the "323" into Chicago in time for 303 to head out at 9:25 AM and I think you could make this work, at least on paper. Call this the "Scott Walker Special": It gets a second train on the MSP-CHI routing without having to get him on board. I doubt you'd get much through KCY-MSP traffic, but I wouldn't be surprised if you picked up a marginal amount of STL-MSP business in addition to the CHI-MSP stuff.
Edit 2: To run CIN-CHI-MSP, the following is something I threw together as an exercise:
MSP-CHI-CIN
Depart MSP: 8:00 PM
Arrive CHI: 5:00 AM (detrain until 8:00 AM)
Depart CHI: 9:00 AM
Arrive CIN: 5:30 PM
CIN-CHI-MSP
Depart CIN: 9:00 AM
Arrive CHI: 6:00 PM
Depart CHI: 7:30 PM
Arrive MSP: 5:00 AM (detrain until 7:30 AM)
You get a daylight counterpart to the Cardinal's lousy Cincinnati timings and a nighttime counterpart to the Empire Builder. It's a long distance train, which avoids having to involve state funds, but you can dump some or all of the sleepers in Chicago (and/or exchange them for more coaches). Even with generous Chicago layovers, the train runs about 20 hours, perhaps a bit more (but do remember: Most or all of your OBS sleeper staff are only going to be on the train for the CHI-MSP segment). You'd only need two sleeper sets (perhaps two and a half if you want a through sleeper to Cincinnati). Realistically, you're looking at almost all of your business being to/from CHI, but then again...a lot of Acela traffic exchanges in NYC even though the train runs through.