I've been eye-balling this spot since I got my Model S 75 back in October '17. A buddy of mine from the Navy was a recruiter station in Kansas City, MO and made this stretch in his Sep 2018 MS75 a couple times. He has the patience of a saint and doesn't mind drafting (at a safe distance) behind semis doing 65-70. The first time, he stopped at the Louisville charger before continuing down to where I was living in Shepherdsville. On his return trip, he left my house and topped off to 100% at the Louisville charger, then arrived in Mt Vernon with about 12% to spare. Since then, he'd visited a couple more times and skipped the Louisville charger, leaving my house with 100% each time.
Until one fateful day... It was December 30th, around freezing temperatures. He had made the drive in the cold before, so that wasn't quite a concern. The big difference this day was that he faced a 15-20 mph headwind almost the entire way. Tesla routed him up through Indy, which he ignored. He blew past the Louisville charger, as he'd done many times before, and head west on 64. A good ways past Santa Clause he noticed he wasn't "regaining" the estimated percentage on arrival like he normally would and started getting worried, but was confident that hyper-miling, slower speed, drafting, etc. would get him there.
Long story a little bit shorter, he didn't. He ran out of range 3 miles from the Mt Vernon supercharger. He was stuck there for hours with a state trooper as they waited for a tow truck to come from a city 45 minutes away because none of the local companies wanted to deal with a Tesla. To make matters worse, his 12-volt died while he was waiting, meaning he couldn't get the computer to turn on in order to enable tow mode, so they had to drag the car onto the flat bed of the truck, then "shake" it off the truck at the supercharger. One of the other Tesla owners at the charger gave him a lift to a nearby store to pick up a set of jumper cables, the hotel maintenance guy brought his truck around to boost his 12-volt alive, and he was finally able to get the supercharger connected and charging.
We've since learned that there's a couple places on plug share that spending about 30 minutes there would have saved him hundreds of dollars, hours of time, and a nasty gouge on his front fascia from where the tow eye pushed into the bumper as it was being drug onto the bed without tow mode engaged.
TL;DR SUMMARY
1. That stint from Mt Vernon to Louisville is doable in a dual motor, air suspension, range mode enabled MS75 from 2018 with conservative driving practices, but you have to have a certain level of risk tolerance to even consider it.
2. Tesla routing may be overly conservative SOMETIMES, but it's usually on-point enough that if you deviate from it too much, you're asking for trouble. (Use tools like abetterrouteplanner if you insist on not following Tesla's route)
3. In the event you do run out of range, always make sure you have the following equipment: Jumper cables (to boost your own 12-volt if it dies), wheel chocks (so you can put it into tow mode immediately upon the car becoming undriveable, BEFORE the 12-volt dies)
They'll get the Elberfeld/Haubstadt charger built someday. I don't even live in KY anymore, I've since moved up to northern Indiana, but I still keep eagle-eyeing that open gap on the map every Monday when Tesla Time News does their "New superchargers this week" and I see there still isn't a blue dot in that gaping hole... But at least eastern Louisville is getting a second charger.