Most people take trips once or twice a year. Sizing your car for a once or twice a year vacation, and carrying all that baggage (weight, cost, etc) in a dailycommute is ridiculous, imo. Just as it is driving a Ford Excursion 4x4 daily in SF Bay traffic because you go to Tahoe twice a year with the extender fam.....rent a car/bus.
My charge time on the Bolt EV is ZERO. I get home, I plug in. It charges while I sleep. The only reason I went Level 2 charging after a year on a 110V EVSE was I volunteered to participate & provide feedback in a peak charge control pilot program with my utility. Fast charging is a necessity for those who have no place to plug in nightly - frankly I'd rather own a house than a $130,000 EV and live in a closet.
500V is ubiquitous for a number of reasons, of which some have already been cited...800V may come, but there's no hurry for commercial reasons, which are also grounded in basic semiconductor physics and in the power supplies servers use.... yup, your Google & iTunes.
The only reason to go higher voltage in my book is to extract maximum HP out of your motor, if you have one that needs 700V, etc. Beyond 500V, everything gets to be a complete pain in the ass - contactors, wires, even the lowly fuse. Even splitting the battery for 500V charging means devices rated beyond 500/600V everywhere.
For what it's worth, the Emrax website site has 800V motors in case people get the idea there has been a correction to that posted here. Overspec'ing an inverter that's already overspec'd is throwing money down a rathole. Using a motor in an 800V battery system that's below the battery voltage is also a dubious choice, imo. Why?
The choice of 800V is questionable, especially for someone allegedly taking a lot of trips with their planned project - remember that NOBODY will repair your homebrew contraption on the road but you, so my general rule, based on several hotrodding ICE projects that broke down during the "trial period" (which can last decades, lol), is don't drive any further than you're willing to pay for a tow home (not to the nearest mechanic). Even there, good luck finding a towing company that will do anything but put an EV on a flatbed (rollback),
Your project, your money, your decisions.