To build a sustainable and crack resistant wall finishes one should consider PVC tiles. On another spectrum one may consider wood and metal with caution.
The best solution for bathroom tiles for mobiles structure is PVC tiles. These are easy to install, do not crack and have the look and feel of real tiles.
You can also use wood finish in bathrooms. Using wood finish also would requires there be sufficient ventilation (fan exhaust) in the room to prevent moisture build up and mold. Before applying wood finish we recommend applying a layer of tar paper then the natural wood. The natural wood needs to be coated with some type of sealant/urthene on all sides before installing.
Metal Panels can be considered and are least expensive and easy to intall on bathroom & kitchen walls.
There are also other options such as painting water resistant paint on high impact resistant gypsum board.
Please download wall type detail and specs of PVC tiles for $10 here: