Having done this drive after the eclipse (and beaten the wave of traffic back to Portland on US-26), using a Model S you might have been able to make it, definitely with the P85 battery pack and no AC (which was not necessary in Madras).
The main concern would be not getting trapped in traffic hell, like any other driver. Getting slightly north of Madclipse and other camps, then immediately getting on the road post-eclipse meant almost empty roads for us. Alternatively, waiting till that evening to leave worked for our friends.
> Getting slightly north of Madclipse and other camps, then immediately getting on the road post-eclipse meant almost empty roads for us
I was in that general area. I was in a farmer's field that had sold overnight parking spots for $50, and allowed sleeping in your car. Here's where it was [1].
I heard the first cars starting to leave the instant totality ended.
I waited until about 4 PM to leave, but still got seriously bogged down on 26 heading north only a mile or so away. It stayed bad through the reservation, then got pretty good until it turned to stop and go for large parts of the way through Mt. Hood National Forest. Cleared up well before Portland and was doing great up until Washington, at about 7 PM, where it was crappy most of the way to Tacoma. I'm on the west side of Puget Sound, so that's where I split off to 16, which was fine. It looked like 5 going from Tacoma to Seattle was still terrible...and this was something like midnight.
Ah, we left the campsite in Madras an hour before the eclipse, stopped off in Warm Springs for food and got north of there before the eclipse. Stayed in Portland the rest of the day (people to see and such), avoiding any traffic on I-5.
The main concern would be not getting trapped in traffic hell, like any other driver. Getting slightly north of Madclipse and other camps, then immediately getting on the road post-eclipse meant almost empty roads for us. Alternatively, waiting till that evening to leave worked for our friends.