Hi there,
The S 75D should be plenty fine for your needs as you have highlighted above. Back when I bought my 75D there weren't many superchargers in Michigan. Now the picture is so much different for the better in that regard. First of all you will have the Marshall supercharger at the junction of 69- and 94 for emergency purposes. Then you have the Lansing supercharger if you again really need to charge. Then heading west back to KZoo you have 2 superchargers in Grand Rapids if things really get hairy. But from experience it has never come to that. As long as you plan a little bit you should be fine. During Spring thru Summer when the temps are above 45 degrees my Tesla gives me phenomenal "mileage" and efficiency. During summers I regularly get a 285 wh/mile mileage. I have gone much lower in usage too but wanted to give you the average number. I regularly beat their EPA number during summer.
During winter make sure you keep a buffer of an extra 20-30 miles of charge especially if you might take 10 mile long lunch break runs. The absolute worst range loss I have seen is once in a while during winters like January negative -20 degree kind of winters where it can eat upto 20-25 miles of range. Perhaps even more so if you are doing multiple start and stops running errands.
That said our Tesla has served us extremely well and range anxiety is non existent especially given their incredible roll out of superchargers all over Michigan.
All of the positives aside I do have to bring you back to reality and point out that we live in this backward state called Michigan. Where, unlike Colorado or California there is NO incentive to adopt green energy or clean vehicles. You don't get crap for putting solar in your house and you certainly get penalized for driving an EV. My Tesla registration fee in the first year was a whopping $625 if I am not mistaken. It went down to like $550 next year and the recent one was like $510 or something. That hurts really bad. I hate living in Michigan for how it continues to act so backward with its policies for green energy/transportation. I hate it.
That said, you will throughly enjoy your Tesla. The Superchargers have made it a no brainer to own and drive a Tesla. Its a car that gives me true joy every friggin day. And driving over daily commutes and road trips when you realize how much gas you did not burn by driving a Tesla feels really really good. ANd feels like you are part of the future.
I hope this helps. Let me know if you have further questions. Congrats on your potential purchase!!