Why the skepticism? It's pretty obvious from the car and supercharger stats that this is trivial to accomplish. I had an easy 700mi day trip years ago in my m3p and the range and chargers are better nowadays.
I'm pretty good at long distance driving (e.g. 14hrs of driving with no stops except gas and bathroom). I could drive 700 miles in a day in an ICE vehicle, but I'd never call it easy. Add in any charging time, and it gets even less so.
I'm not happy with FSD yet, but Autopilot is excellent and really helps with driver fatigue. The charging stops don't really change anything. You just stop when you would otherwise bathroom break or eat.