Why not build one, Charlie. A medicine cabinet is not much more than a five sided box with a hinged door for the sixth side. When you have finished the five sided box--4 sides and a bottom really, you can add a couple of more pieces to the inside and cut out the 2 sides where the soil pipe goes through. A little 1 x 4 oak, 1/4" oak plywood, table saw, saber saw and router is about all it will take. You can "relieve" the space where the soil pipe goes so you will not lose much space inside. Label the big wide side inside the box "hers" and the skinny side with just room for a razor and one can of shaving cream "his". LOL And she will still put some of her stuff on your side.