Wow! I think Tesla will need to rewrite the rules for SC distance, especially for towing! Arriving with 1% in Kennewick means that you climbed a significant hill, then coasted down to the SC. I've done that hill both with a Leaf and Tesla, including with bicycles on the back. Welcome to our "charger desert", just be glad you didn't try it with 5 yo Leaf.
Yeah I hadn't gone that way before and when I saw the hill up in front of me I did my best Tesla Bjorn impression (sheeeit). I'm somewhat curious if someone at HQ looks at the charging data and stuff like starting charging at 1% gets a look over with the car's logs. I ended up diverting to Kennewick because the estimated battery for Pendleton was switching to an exclamation point and Kennewick said I'd have 15% left over (I showed it!)
The two spots I had range issues was between The Dalles, OR and Pendleton, OR which I think I'll try again with another load, and then also from Twin Falls, ID to Tremonton, UT. I had to roll up to Pocatello, ID first and then down to Tremonton, UT. I don't think I can make Twin Falls to Tremonton direct work with a similar load unless the temps are good and I find a slower moving truck to draft behind. The car was crazy thirsty!
There seems to be some L2/L3 charging infrastructure in Arlington, OR, but this time I was past this before it started looking a little grim for Pendleton, and I don't have a CHAdeMO adapter for the L3 so the L2 would have been less than fun. At least with infrequently used SCs like we have out here, pulling a trailer in to charge without unhitching is quite doable, but other L2/L3 chargers who knows as they aren't standardized.
But for the other problem area there is pretty much no charging at all that I can find from the I-84/I-86 interchange down to Tremonton. If they go back and start filling out routes with more SC's in a later phase, somewhere around Sublett, ID might be a good spot between Twin Falls and Tremonton geographically, but there's very little there except a gas station and some llamas.
I rolled out of Twin Falls at 100% and had done some calculations of where I had to be before I got to that interchange to know if I should attempt Tremonton and I was easily 10% under where I needed to be. I believe on that portion I was traveling at 60mph with no trucks for miles to draft behind, temps in the low 40s.
For those curious, here is a log of my SoC's for each leg with the trailer. After my first leg close call I decided to charge longer than probably necessary so I wouldn't get stranded.
P100D towing loaded 5x8 cargo trailer (unknown gross weight, maybe about 1.5 tons):
98% The Dalles -> 1% Kennewick [89.3kWh]
80% Kennewick -> 23% Pendleton [52.4kWh]
95% Pendleton -> 21% Baker City [68.0kWh]
90% Baker City -> 6% Boise [77.9kWh]
99% Boise -> 15% Twin Falls [77.9kWh] (two legs in a row with exact same usage)
100% Twin Falls -> 15% Pocatello [79.8kWh]
82% Pocatello -> 11% Tremonton [65.7kWh] (stupid truck ICE'd center stall making for an interesting time getting in without unhitching).
All of the stops after Boise were after sunset and the temperature dropped into the low 40s and I started getting some "you should charge soon because of low temps" warnings.