How about building the sink into the back of the toilet like they do in tiny houses instead?

Or make the entire room a wet room? Like they do on ships.

@RavenCT The main issue I was trying to tackle was just having clearance in and around the shower, toilet, and sink. Making it open on one side eliminates most of that problem. As far as your suggestion goes, I don't much like the idea of putting those two things together. Incorporating the sink into the shower would make more sense though.

I will say that looking at space-saving toilets, I ran across one that was designed to have the tank built into the wall. However, I'm not thrilled with that idea due to the amount of damage that could be done with a leak (especially a slow one, inside a wall!), and tearing open the wall to repair it. Maybe an older type with the tank hung high on the wall above the toilet would work okay.

@bingst Yup makes sense.

The sink toilets actually let the water you use to wash your hands - then function as tank water - so they're eco friendly.
But the idea of standing over a toilet to get to the sink? Not thrilling... it might be possible to have the sink as part of the shower - though I'm unsure how? I haven't seen that configuration yet.

In total agreement about Tank over toilet being way better than a tank in a wall. Having to dig into walls for a leak would be horrible work.

BTW for a wet room I was picturing a closed off shower area (at least by curtain) - but I've seen that configuration on "Small spaces" shows in European countries. Simply a drain in the floor and a hand held shower head. Pretty simple actually.

Some people survive in really tiny spaces.

@bingst Also these: [pinterest.com]