I did find this on an airline travel website.
As far as US airlines go, Continental Airlines has some roomier-than-average accessible lavatories on their 777s. These accessible lavatories are 45 inches wide and 35 inches deep. Granted, after the fixtures are installed it's a bit tight; with only 23 inches in front of the toilet and 21 inches on the side of the toilet.
The lavatory in the trailer is 36" x 60" including a 24" x 36" shower. Making the lavatory area about 36" x 36". I have 15" in front of the toilet and 17" to the wide side, including the counter.
The Lavatory in this photo is just like mine.
Taking a shower the first few times was interesting. The ceiling in the trailer is low at only at 76" and I am a little tall at 74". The shower sits on top of the floor, so it is raised somewhat. You actually step up into it. I don't fit, fortunately there is a skylight directly over the shower and my head sticks up into it.
Then there is the problem that my arms are longer than the lavatory is wide. I can't wash or dry my back without banging the sides of the shower or sometimes the ceiling. Because of the limited space I can't dry myself as I normally would, leading to all sorts of contortions to dry my back and legs.
I guess this proves you can get used to anything. I got a back brush and a couple of 3M medium hooks along with a body scrubber on a a string and hung it in the shower. I can now take a shower with only a little inconvenience. One nice feature is the shower is on hose and the shower head can be lifted out and used as a sprayer.
I won't describe the contortions required to operate the marine type toilet.