Mailbox Alert

Mountings for components of an alert system that alerts me when my mailbox is opened.

My mailbox is about 150 yards away from my house, and can not be seen from my house. I was looking for a way to alert me when my mailbox was opened so that my mail would not sit in the box all day for someone to steal.
Most RF systems I looked at had very limited range. I finally found this one: https://www.amazon.com/gp/product/B07Y3WLWKF/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1

This allows a remote switch to be attached to the transmitter which is necessary since my mailbox is metal and would block any RF signal if the transmitter was inside the box.

I bought these reed switches: https://www.digikey.com/en/products/detail/RI-02GP1520/1835-1006-ND/7497024?utm_medium=email&utm_source=oce&utm_campaign=3480_OCE20RT&utm_content=productdetail_US&utm_cid=412483&so=67157981&mkt_tok=eyJpIjoiWVRWbE5EVTVZVGcxT1dSaSIsInQiOiJHeWc1XC9JMHN1c0JTRzllZW01QWN2d1EzTzZpSnducm0xQUI0ckpDdGhsZDVzREJuWVJne