a great place to start looking for things designed to take less space: travel
but i don't mean travel sized shampoo and toothpaste. if you want to make a compact well equipped travel vehicle, like a vardo-not-the-own-in-sweden, look to the history of the travel vehicle
please take a look back in time with me at the pullman car
that's right - fold up/down sinks. i mean, if you have to make a teeny tiny itty bitty bathroom, why not move things out of the way when you don't need them? a sink that folds up into a few flat inches is ideal.
this reminds me - there's a row of cabooses here in town on the side of an embankment on unused track. currently they are graffito canvases but i wonder if i could ever find the owner and afford to buy one?.... *google* - huh, looks like there was an article about them just a couple of weeks ago and they are for sale