The prime purpose being to shut up all the naysayers on range so that on the 4 times per year people need to make a long long trip, they can keep their EV batteries topped up with a towable trailer. Quite why they can’t pull in and take a bite to eat and supercharge after 200 miles / 3 hours of driving is beyond me.
Ideally the trailer should also be available as a rental item available from the nearest Tesla dealer or local equipment hire company of choice.
It would be even better if the generator could be used to provide silenced remote site power whilst on wilderness camping trips. And the trailer could also provide additional storage for bulky and / or dirty items like bikes, surfing or camping gear to keep the car interior clean.
If then becomes a real lifestyle accessory and makes a Tesla the only car you need. For commuting, long distance family holidays, trips to the home store for buying furniture and building materials, or to the recycling centre to drop of garden waste. Ok, it won't do off road, have a 2ft fording capability, or be able to tow 26ft sail boats, but still do for the other 99% of the world's drivers.
You could give the trailer a 8ft bed base with dually wheels and no one needs a big truck anymore. ;-) I’m joking here, but you get the idea. Instead of buying a vehicle for perceived occasional needs, you buy the traction vehicle as a model S/X/III and accessorize the load and distance capacity as and when required.
I know this doesn’t fit in with the ultimate goal of electric only power, but if it shuts up 90% of the people who on every EV forum thread that says “it can’t do my annual trip from X to Y which is > 250 miles” the world of internet forums would be a more peaceful place to be. It doesn’t matter if not every Tesla owner ever uses one, but if they are available for use, the battle of minds is won