I look forward to hearing your success!
Forgot to post the success! No flat bed needed, but it was close. I made it both there and back with 3% remaining. About 218 miles from the supercharger to my house. Google says that Indianapolis Supercharger to Springfield, IL Supercharger is 220 miles.
On the way over, it was ~70F out and I averaged 284 whi/mi (61.9 kWh) for the 217.8 miiles.
I really picked the speed up past Champaign since I was feeling confident. The -9% on arrival was way off obviously! I think I could have made it with 8-9% battery left. Somewhat conservative driving, mostly speed limit cruise control.
However... on the way back to Indy, it started at -13% estimated on arrival. It was MUCH colder, closer to 40-45F, and I ended up driving 224 miles (started 100% from in-laws). I was at 278 Wh/mi going the absolute speed limit or slower the whole way home. 62.3kWh used total. I was pretty nervous to be honest.
I'm not sure if I would attempt Indy to Springfield:
1) Under 40F temperature
2) In a 60!
3) Without an hour to spare in Champaign
4) a year or two from now when my battery has lost some range
Please, please please bring a Supercharger to Champaign, Tesla! I know it's the same for the Country Hills to Effingham route. This location would serve both of those main midwest thoroughfares -- and to just get 10-15 minutes and get back on the road would be huge. Definitely not paying $8.50 to park at Hyatt to charge on 40amp, and not wanting to risk the charger at iHotel being used on arrival. Tough choice.