I found a small water-resistant zippered cordura pouch that is about the perfect size to hide a radar detector inside. The bag was originally made to contain multimeter test leads, and I happened to notice it in the pile of clutter that I call my office the other day. The material is PVC coated on the inside, so it should help in a light drizzle, but of course the zipper is not watertight.
Today I mounted a RAM Hot Plate (magnetic quick mount), and re-routed all of the wires needed to perch the RD on the top of my tank bag. I figured that in the event of heavy rain I'd be putting the rain cover over the tank bag, so the RD will be covered too. It will also make it super quick and simple to take the whole shebang off at night in one piece at the hotel when traveling.
Obviously, I will not get laser alerts, but previously I was running the RD in the glovebox, so I'm used to that. Besides, when the laser alert goes off it's just a signal to pull over and accept your ticket anyway.
Here's the obligatory pictures to prove its existence:
This is the zippered pouch mounted on top of my Bags Connection Daypak 2 tank bag. The lid of the bag is semi-hard and supports the weight of the detector easily. You can also see the remote display and mute button over on my clutch reservoir. I'll probably also add a safety strap running under the Hot Plate and over over the top of the pouch, as I know that the RD will come off the magnetic mount under certain circumstances if used alone (like hitting potholes or deer)
The RD unit just drops into the pouch, connect the cables and zip it up!
We'll see how this works out in the long run.