Consider this before you use them for "tailgators"...It is illegal to have a rearward facing white light while the vehicle is in forward motion. So while most of us would like to have something to get a tailgator to back off you will get a hell of a ticket if a cop sees you do it. And with cell phones everywhere one is only a 911-dialing away if you piss-off the wrong person.
Also, you'd have the "flash-bulb blindness" effect for the victim. If you flashed a tailgator, temporarily blinded them which resulted in an accident which may even involve other innocent motorists/pedestrians...now you get charged with some serious felonies.
I'm not saying having adeqate illumination for backing up is a bad thing, I could have used better light this summer when we were camping in Montana and if it weren't for my wife ground guiding me it would have been difficult by myself.
You may consider a model of light with a cover that can be flipped up when you need to use them. That way tempation for "illegal actions" would be removed. I'd mount them high too. Most work trucks I've seen them mounted to have them as such. Also it would avoid the ground breaking them off if you clipped them while negotiating grades.
I see your point, it's a good idea but I will probably never follow through with it. However, I am most certain I will be buying after the market foglights, but have to wait for that one attachment to make it look good.
Just wire them into the power supply for the OEM back-up "reverse" lights so they only come on when you put the verhicle in reverse, thus avoiding "blinding" tailgaters and going to jail.