We are remodeling a bathroom and want to put in a closet with roll out drawers. The space is only 18 inches wide but 3 feet deep so a door frame would dramatically reduce the usable space and it is not positioned for a pocket door. How do you build/install a door where it must hinge directly on the wall?
With such a small space I would ditch the door entirely if you want the rollout drawers. Build a wood face for the hole and you can put your drawers and shelves or whatever you want. You're essentially making a cabinet. I just did a closet very similar to yours for a customer. I faced it with oak and had two pull out drawers on the bottom and I made a door for the top half with shelves inside.