I ran a test a few weeks ago with my R1T towing my Keystone passport trailer at 55mph (about 4000' of elevation gain). It went 126 miles on 91% of my battery (efficiency was 1.11). I'm eyeing a Canada trip with my family later this year and there is one leg that is 144 miles between chargers. At this point I'm going to take the chance. I'll probably drive 50mph to be safe at first and if I need to unhitch close to the charger to go get a bump charge, I will.
I towed this same trailer with my '21 F150 Powerboost this summer. Efficiency dropped from 21mpg (unladen) to 8mpg with the trailer and bikes. Even with a 32 gallon tank I was stopping every 200 miles to refuel. Speed was more like 65-68mph. We are getting closer to these two being matched. If the Long Range pack gives you access to all 180kWh you'd be right at 200 miles of towing range at 55mph. I feel like this is minimum. To match my F150's efficiency (at 65mph) I would need a 280kWh battery pack - more than double what I have right now. At 55mph that decreases to 240kWh.
This highlights the need for more EV chargers on secondary roadways and in states that have points of interest but few chargers looking at you AZ, NM, WY, MT, SD, ND, and parts of Texas. I'm sure RV parks can be used depending on how updated they are but I typically do more remote camping so range is a big deal.
ICE traveling with loads or trailers isn't much of an issue since you can find gas stations without much effort.
The current Texas EV charger proposal is every 50 miles and an added focus on rural roads but that is a multi years effort.
Once we get bigger and/or more efficient battery packs this is the life of EV truck drivers towing something large.