Let me just add my .02 to this thread, if you are planning on towing and need to rely on anything other then superchargers or fast charge DC station for in between stops - come up with a different plan - especially in cold weather. We have MX P90D and recently sold our cabin and needed to move some stuff home (190 miles). I own a single axle Aluma utility trailer 6310H and with the trailer empty in winter at 53MPH I'm getting 550WH/mi or about 120 to 130 mile range with the ramp off (trailer completely flat and this is a light trailer ~600lbs empty). I towed a double axle 6 foot by 12 foot enclosed Uhaul trailer for one trip, and it was way worse ~100 to 110 mile range at 45MPH 625WH/mi.
In my opinion, 45MPH is not a safe steady-state speed on any road with people trying dangerous passes to get around you. Even if you have a supercharger in range they are not designed for trailers and unhooking is a pain. I started leaving at 10PM and driving overnight to 6AM to avoid traffic and have empty superchargers - but never again. All the trips were very frustrating with the U-haul especially bad sitting at J1772 at a car dealership 30 amps for 5 hours trying to be able to get to the next supercharger - a truly terrible experience.
I'm also very dissapointed in the trip planner and on-board energy monitoring when pulling anything - the Tesla software can not be relied upon to give accurate estimates of range even at very slow speeds. I just stared assuming 1 to 1.25 mile for every 1% capacity at 53 MPH. The vehicle itself can handle the loads, but with current charging infrastructure and battery capacities, EV's are just not suitable for towing more then 100 miles total. Even then, be prepared to tow at night or the trip to take six times as long...
