Charging a Leaf from a 22kVA mobile diesel generator must be a bit of a joke, though it is a good demonstration of why the AA have to recover stranded EVs with a flat battery rather than charge at the roadside.

The battery trailer may look a bit silly, bit as a concept it's a really good idea. Most cars travel less than 100 miles most days. All EVs can do that easily, but they can't do the longer trips which most people only do occasionally. Why pay for and lug around an extra few hundred kg of batteries all year for those occasional trips. Far better to attach it to the car only when it is needed. If this can be done on a rental basis so you don't pay the capital cost and they are interchangeable between different car types even better.

The French are far more into small trailers than we are. Over here we buy a big car with a large boot to carry stuff a few times a year on holiday and then spend most of the time driving it around 1 up in town with nothing in the boot. The French would instead buy a Clio and a small luggage trailer to use on those occasional trips when more space is required.. A far better option, and cheaper too.

Most cars travel less than 100 miles most days. All EVs can do that easily,

No they can't. The Honda E might manage 100 miles in ideal circumstances, but otherwise it won't. The Mini Electric would also struggle, certainly in winter, and the new Mazda MX-30 has a similarly short range as the Honda.

Or just get petrol/diese (or even hybrid) car and problem solved B-)

Electric may be the future, but let us enjoy the present first.