My Great West Van Legend has a slide out of the away into a wall lavatory. I believe one of the small B Sprinters had one too. The Leisure Travel Van Free Spirit T1N Sprinters had flip up lavatories. There may be others. One of the features (advantages?) of a wet bath is you can sit on the toilet seat while showering. That is one of the advantages for washing feet and legs in a small space and for women shaving their legs.
My Legend has a complete surround around shower curtain and cover for the toilet seat so ultimately the only hard surface that gets wet is the floor. The space is 25" x 41" which is bigger than a lot of 24" tiny square separate showers I've seen in RVs. The doors pop open to create an enclosed space utilizing the van aisle for extra room. With the doors open it gives you more elbow room in the 25" direction pushing elbow against a curtain.