ThermoPro remote sensor mounting box

I purchased a ThermoPro indoor/outdoor thermometer from Amazon to mount in my travel trailer. https://www.amazon.com/gp/product/B07L82PF1Z/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
The mounting provided for the remote sensor is pitiful, a single keyhole slot for one screw, not good mounting for a road-going vehicle. Also "waterproof" in the summary seems to mean "don't get it wet" as described in the user manual. So, I designed and printed a little box to contain the remote unit and moun