For 150 miles, wearing 18" M+S, I think I'd be comfy. If you were considering soft-compound 22" summer tires, I'd be less confident and want a backup plan (a DCFC on route to throw 15 min of juice in).
The only "freezing" 150mi trip we took was IIRC, 28-36°F, 75 mph, Norco to Santa Barbara in Feb, coastal mountains wearing 20" All-Seasons. On the way up, 31% left, return trip (colder, not 100% SOC, used battery to melt ice on windshield) left 18%.
That's just my experience. And 75 mph around here is not safe since N-side black ice from runoff can occur at higher than 32°F, plus it's speeding by 10mph over which can get you ticketed.
But... We had two people, and luggage. This will actually improve your heater performance at the expense of rolling resistance and hill performance. I believe the coastal mountains are puny, at 2400' max perhaps. But in freezing weather at 4500' is was not tragically bad, but there was little snow when I went North. A Better Route Planner says the I-Pace will not be able to complete trips I've takes at 70-81 mph even if I slow to 35 mph. So you will need some first hand results.
Bjorn Nyland test the Tesla, I-Pace, and eTron in snow country (Norway) on wet roads in freezing type conditions on M+S Conti's. It might be enlightening.