Can you put a keypad in the wall if so, why not just choose something simple like a
Xantech Waterpad, you can use IR directly through the keypad and need nothing else but a connecting block and an emitter.
If you cannot install something into the wall, then the U1 would be the best bet with the Apple iPod dock, since there is not really much control with that device, and the U1 is cost effective at that point.
The RP-1 & U1 combo is fairly simple to put to work, especially for a situation like that, where you are only controlling one product.
There are other docks that work much better than the Apple dock, but for your situation, it just might not call for it since total shower time may only be 10-20 minutes, so there is no need for playlist scrolling, genre/artist selection and so on...
I personally like the URC iPod dock, the control set with them are just amazing and very flexible, but I usually use them with 1-way scenarios and touch screen remotes that allow for more information to be shown on the remote.
