Personally, I use the Krown rust control and lubricant spray in my hitch ball/receiver.
I keep mine in at all times regardless of me towing or not. Yes... I get it, it's sometimes considered not etiquette, or necessarily allowed by local governance... Do I give AF... not at all!
However, this is my "bumper protector", and I use the "tri-ball & hook" combo piece with the extended length (in black chrome so it looks good on my truck...lol).
You'd be surprised at how many times over the years this has come in handy due to the f_ c..u - K _ ta//rd_- er...*y of drivers out there be it in the drive-thru or parking in a lot, say Wally's... where they come right at ya and smack the back end!
I had an instance a year or so ago when dim..wit at Tim's drove right into the back of my truck...
My hitch went right into his grill and A/C condenser.... I had a scratch on my ball... he had a couple thousand dollars damage... I told him he could go through insurance (private property or not!) or just eat it and I was good to leave.... He chose not to report it to insurance and left with a hole in his grill and an A/C system that was damaged... due to his ignorance....
Had I not had my hitch in place.... my colour matched rear bumper would have been hit and that would have indeed been an insurance claim