Well, not a cool thing I did but what I'm hoping to achieve. All comments welcome. Edit: mod completed! See post #4
Currently using a Hue Outdoor sensor pointed at my driveway to trigger external lights. However every time summer rolls around I get a ton a false triggers at night which I suspect is due to heat radiated off the driveway.
So my plan is to get a standard wired Bosch tritech and simply hook up the NC relay output to a xiaomi window sensor (although these are getting harder to come by these days). I have a few still and they are ideal given their tiny PCB once the case is removed, and should hopefully fit in the Bosch case. They will require at least 9V power which fortunately I'm able to provide at that location. Although the case isn't IP rated I figure sealing the edges of the sensor plate and duct tape for the main joins should be sufficient given that it will be under cover and away from direct rain and sun.
What do you guys think? The basic wired tritechs are fairly cheap whereas the zigbee versions are pricey and hard to get hold of over here.