Well if you're building the closet (meaning there is no front wall yet), you can build it as deep as you want. I only said that most closets are 24" deep.
As for me, I would wonder if I saw a closet that the clothes bar was much lower than eye level - and I'm not really tall. Now I'm not about to do the math for you.
I lived in a Cape-style house when I was younger. The second floor bedrooms sloped down at both front & back. The closets were on the end walls and were normal height with a normal doors. However they went deep to the side, giving you a normal looking closet with room for lots of storage. If you did that, you might even put in a second clothes bar just high enough for shirts & blouses, at an angle to the main bar.
The interesting thing was that the previous owner had built in bureau space into the short wall....three drawers of clothes tucked out of the way, taking up zero floor space. Of course thee was no table surface provided by that, so you still need some sort of furniture.