I gave that some thought as I was figuring out how I was going to do this. I stopped by a dollar store looking for something smooth, low profile and easily modified. That's when I found these.
As for the wire, although I got a cheap 20ft section of 26 gauge speaker wire from the dollar store, I was able to just use the original wire that came with the unit (my enclosure is not real big). It would probably work the same for a rack system too.
FWIW the sensors are all waterproof. The big thing is to use hot glue to seal the exposed wire preventing any possibility of a short.