Could you get a small scissor jack, wrap it in something and tuck it under the spare wheel maybe? As the car is so light you might be able to find a really small one.
But you're right, for MMC to design and sell a car that can't carry the means of changing a wheel shows just how out of touch they are with people who like to drive long distances.
That’s what the previous owner of my 4/4 Sport did Tim. He bought a small scissor Jack and handle kit from Halfords and I ‘liberated’ one of the Memsahibs hessian Bag for Life’s as it stopped rattles and protected the car. Tied it all into a small bundle with a luggage bungy.
BR
Colin