Imagine if Nissan buys a load of these and stocks a few at each of their Leaf-selling dealerships for FREE loaning to Leaf owners going on roadtrips.
You could reserve it in advance if you wanted to make sure you'd have one available, or simply wake up one morning, verify by phone if the local Nissan dealer still has trailers that day, and leave immediately with your gear packed in your Leaf for a little detour to pick up that trailer and you're on your way.
(I assume you can safely charge while driving, otherwise yes it's pretty useless.)
That way you save $8,000 ($11,000 in California) and get 100 electric miles instead of 40. The downside is that you have to start every >100 mile roadtrip with a detour by the local Nissan dealer. Probably worth it...