In my experience, it takes a few trips for the navigation computer to figure out what your range is going to be based on your trailer. But it does seem to get more accurate over time. I have a similar size trailer and rarely get much more than .95kWH per mile. Your max battery pack probably has...
We pull an Imperial Outdoors XR22 off road trailer. Honestly it’s more off road capable then we need, but it is a toy hauler and it’s very handy for taking 5 kayaks and 5 bikes and all the camp stuff. We only take it locally with our Gen 1 R1S Dual Max, it only gets about 140 miles on a charge...
That looks like a lot of fun, one thing to keep in mind is that your suspension studies should be set on firm, especially if you’re towing a heavier load like my travel trailer.