Tail gate down indicator

I'm a huge F-150 fan! My dad owned them while I was growing up in the old days - my D.O.B. 1949 - and I got addicted. I have owned 5 and presently drive a 2010 from Capitol Ford, Madison and have loved every one of them. You may have already had this suggestion many times but, one thing that occasionally happens to me is that I accidentally leave the tailgate down and have come close to backing it into something that would have done major damage. An indicator light that informed of a down tailgate, that turned off after a minute in case you actually wanted the tailgate down and didn't want to look at a warning light, would be great. Keep up the great work, you'll see me at a Ford Dealer again!