Weigh and durability is my concern about using any sort of tile in my bathroom, as far as on the walls are concerned. Really haven't even begun to look at what to do with walls, though there is a Classic motorhome owner that used the tiles on his bathroom. He's driven it from New York to Alaska and now Arizona. No idea how the tile has held up.
Jerr1955, possiblities are endless in how you configure your bath. Look at how some manufacturers are doing baths now. Seen some where there is a toilet/sink, across from the shower. Toilet/sink area has a door, that when opened makes the whole area into 'larger' bathroom.
Personally, I wouldn't dedicate a lot of area just for bathroom, especially considering that you don't have a lot of square footage to begin with. Get to the Tampa RV Super Show at the Fairgrounds next week, walk through all of the Airstreams, and then start looking at trailers and motorhomes to see how their baths are done. Some are totally impracticle, others will give you some idea of how you'd like to set your bathroom up.
Good Luck, Derek