It's here, it's real--the genset trailer for your Makita powered car...

Seems somewhat self-defeating in more ways than one; besides the obvious of using an ICE to charge your EV, the act of towing a trailer will cut down your range requiring more frequent use of the generator...
I see these more as something to be used by AAA roadside assistance when your EV dies in the middle of nowhere.
If you have enough problems with range, why not just buy a hybrid, instead of an EV?