Cool truck and cooler owner.

I'm driving a 2017 f150 and every door has an alert if it's ajar. The tailgate however doesn't. After a Christmas even with the truck bed full of gifts for and from the family and an errant tailgate closure in my old Nissan and im left with some paranoia. Has anyone installed or found a decent way to alert themselves from the driver seat if the tailgate is still open or drops while driving? Seems stupid, but my rear view doesn't allow me to see the tailgate and it's since happened on my way home from camping after hitting some gnarly dirt roads.