John
Rack’em Up!
I found a gasket ring from a plumbing supply store (the type they use for larger diameter pipes). I glued it to a pvc pipe fitting to hold it down, and this covers the label area perfectly and protects it from the cleaning liquid. Total cost was maybe $4.
I used two of these with the included gasket, drilled a hole in it and purchased the screw-on knob from the same hardware store.
http://www.hardwareandtools.com/Bell-Weatherproof-5374-0-4-Round-Blank-Cover-Plate-Gray-6199145.html