When I was looking at a SOB fifthwheel bunkhouse, I saw one that had a toilet mounted in the shower and had a sink in the corner of the shower. Somewhat like the Japanese bath shown. However the overall room was tiny. I swear it was less than 3 x 5 total in size. and very crowded. It was somewhat similar to a wet bath from the days of popup trailers.
Do you really want RV builders to build an even smaller bathroom that is even more cramped than the ones they are building now? That may be why such a small girl was demonstrating the Japanese bathroom.
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Home depot sells a conversion kit for a sink over the toilet tank
http://www.homedepot.com/p/SinkPosi..._-205088518&ci_src=328768002&ci_sku=205088518
Toilets with integrated bidets are sold at Menards and other similar places.
Whirlpool baths with heaters have been around for years.
So yes, this stuff is used outside of Japan.