I'd probably take the Utah route one way (Beaver to Page to Flagstaff) and the CA route the other. Check the weather and make the appropriate decision.
You'd save about 30 minutes driving time going through Eastern Nevada (Twin Falls to Wendover to Ely to Vegas), but you'd need to figure out some sort of overnight charge in Ely and even then, you'd have to get a full charge and drive carefully on the Ely to Vegas leg. I'm assuming you have an X100D so this should be doable in winter due to the elevation drop. Do not attempt in the reverse direction (you'd need to charge in Panaca and who knows how reliable that is... one entry on Plugshare). All in all it's probably not worth attempting the Eastern Nevada route, especially in winter. At least not until they put a supercharger in Ely.
There's also the route through Reno, but the Reno to Vegas drive is famously boring (admittedly the Ely drive isn't much better!) and all of the paths that connect Reno to I-5 (at Redding, Mount Shasta or Eugene) can be extremely snowy in winter) so I generally wouldn't recommend this one.