(Apologies in advance; I was not successful in embedding either images or youtube)
Came across this little fiberglass standy built in the UK called a Go-Pod Caravan. Interesting to check out for the design elements. I converted the price to US dollars = a bit under $13,000. It has a low profile for towing, but there is a little canvas pop up section that allows the user to actually, well, stand up.
The other caravan of interest is called the Adria Action 341PH+ -- again, interesting European design elements. Also a tiny standy, it has an amazing amount of space somehow, with a giant storage area accessed from the outside and a pull out double bed, plus a bathroom with an ingenious fold out sink. Click on this link for photos.
This is a youtube link showing the Adria Action 341PH+, so you may be treated to an ad to begin, but you can opt out after a few sections. I was not successful in imbedding the youtube link in this post, but the link is here.
I suspect there is a major market for tiny standy trailers in Europe and the UK, because people tend to have much smaller cars, due to the high price of gas. Also, campgrounds tend to be crowded at some times of the year, and in the UK there could be lots of rain, so there may be a strong preference for at least some privacy and a place to get out of the rain.