As for tiling under and behind.... yes it would probably work, but you'll need to learn about waterproofing under and behind the tile. Tile and grout are not waterproof (surprise!)

Look into a product called Kerdi from a company called Schluter. It's made for custom tile installations and shower pans. Can be done to fit any size or shape of area. Note that the floor drain you use must be their design also -- it gets water from under the tile as well as over, into the plumbing drain.