As a Missourian who's been driving an S85 for almost 3 years, I think I can offer some insight into your decision.
1)Where in Missouri will you be living? Much of the state and surrounding states have no significant EV infrastructure. I live in the Springfield area and it is very difficult to get anywhere from here (St. Louis, KC (not bad really), Columbia, Tulsa, and Little Rock are all close enough, but barely for the 85). But if you'll be in St.L or KC area, your needs for Superchargers will be less and EV infrastructure in general (esp. in KC) is much better. Thus an 85 is important for me, if I were in KC or STL, 70 would suffice.
2)Where in Missouri--as regards weather? I've gotten by with RWD only even in some fairly sketchy winter weather, but I can tell you there were a few times I was wishing for front or AWD and a few trips I avoided for lack of same. So, again, if you're looking at rural MO where roads don't get plowed for hours or days after a snow or ice storm, then I'd lean toward AWD--that said, if you're in a rural area, you're more likely to ALSO need the 85kWh battery. I do have tire chains and they've saved me a few times. If your wife is driving, she may not be as inclined to try to put those on.
3)Rated range-when new, the 70 is likely quite adequate (other than the aforementioned longer trips), and you can hope that Tesla will meet their near term Supercharger goals and have adequate infrastructure to meet the needs by the time your range delines on the 70. For me, had I gone with anything other than the 85 3 years ago, I'd be in a real bind to get anywhere outside of the local Springfield area...even KC, in winter or strong rains is tough.
My vote, if you simply can't do the 85D, would be the straight 85 unless any of the above issues would sway your decision.
