I would like an accessible toilet if I had the opportunity to design that into my plan. I am not sure how much space you need for that but if you took the wall with the pocket door down that might be enough. 5' radius comes to mind but that might not be the dimension so don't take my word for it. The shower looks long enough that you wouldn't need a door. I've heard people report that their 5' square showers are ok without doors. The windows at the tub will need to be made with tempered glass I believe for code. The window in the shower will need to be special in water proof design and probably tempered, unless it is a clerestory window. I bring these points up as a novice, not someone who has direct experience to these specific elements you post about.

We are dealing with the same issue only in a basement. A friend just had an accessible shower put in, she is in a wheel chair. Her handyman fella designed a metal lip to roll over. She is experiencing no out spray with just a curtain that hits just above the floor.. Here DH goes back and forth. The slope has to be perfect for it to work out...We want the no lip so as not to have a tripping hazard so near the sink..very small bathroom..AND we want to maximize the shower area....

Draw a line directly across from the end of the shower's stub wall. It need to be 4' from the wall at the top with the head. That line marks the beginning of the sloped floor for the shower. Use a trench drain located at the top wall. You will use the steeper 1/2" per foot slope for the shower area. I would suggest a freestanding bench or a fold down one for more stability.

With no dimension listed. It is difficult to see if your plan would be compliant or noT.

Thanks for all of the feedback. LWO it sounds like you're recommending that the floor slope start at the point in the pic below with the 4' 11" line. With the current plan the stub wall is 6' 8" and there is 3' 5" of clearance between it and the pedestal sink. My understanding is that the total slope needs to be 2" down to the drain. If this is correct, I'm wondering about taking the clearance down to 3' since a 7' stub wall would equal a 0.3" per foot floor slope. Does this sound right? And is 3' enough clearance between the wall and the sink?

Exactly what Live Wire wrote. I'm guessing your floor "tiles" in the drawing are a 1' grid?

Referencing your last drawing, you could have the bathroom floor tiles and the tiles in the shower space that are below the 4'11" measurement all flat and in the same plane. The break in the floor where the shower slope starts will be at the end of the sub wall, right on that 4'11" line.

A 6'8" stub wall will give you about 3/10ths" of drop per foot of run to get your 2" drop.

A 7' wall will shallow it out a bit, a little over 9/32nds" drop per foot of run. Get out your micrometer and your magnifying glass. lol

For wheel chair considerations, personally? I'd rather have an extra 4" of width at the shower entry and accept the shallower 6'-8" depth.

Water spray really won't be much of an issue with your head 4' away from the threshold.

I recommend you use a topical membrane on the shower floor; both on the sloped shower floor and on the "flat" shower floor (total 11' by 5' shower footprint), and also extend the membrane outside the shower door a couple of feet onto the bathroom floor.

I'd do a shorter stub wall for better clearance. And eliminate that window in the shower. It's asking for leaks unless it's a clerestory.