Yes, i did something very similar. I did the design myself, but hired hired a contractor. I don't think its a DIY job. We moved our toilet and the tub drain was also shifted a bit to handle the new freestanding tub but i found one with an end drain so it wasn't much of a move.

I assume this is a total gut job? Floors, etc?

I would be happy to give you some input on the design if you post a drawing of the space with measurements.

Here's some pics of mine. I stole some space from two closets to make this work - but it was well worth it. We originally had a wall separating the shower and toilet areas from the sink and tub areas. I also replaced an old garden style window and its so much more open and brighter now.

Here's some pics of mine.