While it was possible to mount the normal unit at the back door because it is deeply protected by a large carport, placing one at the front door meant dealing with sunlight and rain in perpetuity.
Step 1: Choosing an Enclosure.
That meant a fairly large box, which meant I could choose a very nice inviting button to press.
Although the box was supposed to be UV-resistant, I decided to paint it for both further protection and aesthetic purposes. The black plugs at the back are screw covers to help keep water out.
The second photo shows how the basic unit sits comfortably beside the big switch.
All that is required is to screw the front panel back onto the box.
The transmitter receiver pairs allow for a selection of 16 "tunes", most of which are pretty horrid. The choice of "tune" was fairly easy. I set the front unit to generate the stand "ding-dong", and the back door unit to "barking dogs" because of the dogs in the next door neighbor's yard.
Future modification: Next time it needs opening up, I'll have a super-bright LED to install in the facia, connected in place of the activity LED on the circuit board. I'll actually choose a LED that requires slightly higher voltage than the existing one, because when these units failed, the LED was still flashing to indicate that everything was working fine. A LED that needs higher voltage will fade out sooner, so that it's more obvious that the battery is failing.