I don't know what you have in mind. There are various options, ranging from a bare wall lined with shower curtains suspended from hooks, to ceramic tile applied to a "waterproof membrane" covering either cement board or plywood.  Below is my inquiry to Lowe's, from whom I received an obviously prefabricated answer.

In the two bathtub enclosures which I tiled in Konnarock, I applied the ceramic tiles without waterproofing to the painted plaster from which the plastic tiles had become detached. In the three bathrooms which I tiled in the Addition, I applied the ceramic tiles to cement board without waterproofing.  I don't think Tim used waterprrofing, other than the cement board, on Nantucket. If you want the highest quality, I suggest we use cement board (Durock or Wonderboard) coated with a "liquid applied waterproofing membrane".  The tiling itself might (or might not) have to wait for a later trip.  

The cement board (3x5) would fit into the cargo space. When it is cut with a saw, it produces hard to clean up dust and dulls the saw blade. If the "liquid applied waterproofing membrane" is reliably waterproof, I don't see the advantage of using cement board rather than plywood.

As always, I'm happy with whatever you decide. 

Here's my inquiry of Lowe's: 

"I wish to build a bathtub enclosure with 1/2" plywood covered with waterproofing paint and ceramic tiles. Will this work? What paint which is both waterproof and to which the tiles will adhere, do I use?"

Here's the answer:

To prevent water damage, you must install a waterproof membrane just below the tile bonding mortar as close to the tile as possible. There are two types of waterproof membranes, sheet, and liquid applied options. The walls encasing the bathroom must be waterproofed up to 150mm. Hobs should be waterproofed up to 100mm. Wet room bathrooms (bathrooms with frameless showers) will need to have the whole bathroom floor waterproofed as well as the walls up to a 1500mmradius.