I think all modern textbooks should use it as well. We could still use the metric system, but instead of the base units being centered around water, they could be centered around a '62 Chevy. Instead of metres, it'd be the width of the front seat, instead of tonnes it'd be the weight of the engine block, instead of freezing point of water it'd be the temperature at which the engine just won't turn over on a cold morning... it could work!
To be fair, the news seems exclusively to report area in tennis courts and "the size of Wales"; I'm beginning to suspect they're SI units.
I'd forget all about units of measurement. My advice would be to paint a picture. To quote some other member... "The house was barely big enough for a bed and a small table..." Let the reader do the work. Do you know the name of the biggest nation in the world? Do you know how big it is? It's the "Imagi' Nation and its huge.