Yeah - too bad about the color. The $10K more for the 100Kwh battery is a steal, though. I think it's about $16500 spec'ed on the ordering tool, so that price savings on an Inventory Model X 100D might be worth it if they found your color combo. I wonder if regional Galleries & SCs can query other Gallery/SCs' inventory. You'd be eating $2500, and paying $10K-12K more -- plus a flight to pick-up the car (unless they shipped it) but even then you'd be saving around $4500 over what a new 100D would be.
A lot to think about, but ultimately I think you can make your commute with the 75D. It just will be fraught with having to think a lot and watch the range closely. Worst case, if you tire of that and having to think about each drive / monitoring your battery & range like a hawk -- you could always sell the X and switch-up in a couple years or so.