I believe that it's perfectly doable with a 30" deep drawer at the bottom, as long as the plumbing under the sink allows it, of course.
You also need to use ~1/4" thick pieces of filler on each side of the sink cabinet, as the door would be slightly larger than the width of the cabinet when used horizontally (the fillers do not need to be finished, as they would be covered by the door when closed and by the trim around the sink front).
This also assumes that your carpenter would know how to deal with the required holes on the door (2x 3/8" for attaching the drawer rods) and proper screw locations for the front fixing brackets used to attach the front to the drawer.