Proximity Sensor for 1984 Porsche 911 Front Bumper?

I've got an 84 911 that keeps getting backed over in the front. the car is pretty low, so SUVs seem to be backing up and breaking headlights, denting fenders, etc.

All I want to do it put a sensor in the front bumper, or at either corner such that when a car (or anything) comes within 8 inchs to a foot of the front bumper, the horn will sound.

I'm good with mechanics, work on the car myself, but have no idea on what I need to make this all work.

Thanks in advance for any help you can give.

Need a police style grill guard. :) Since your bumper is not liekly plastic it might be possible. Remember not to mount it on any metal. The trouble is that it might get wet if your not careful.
Also if their a's enough to back over your car (literly) I would seriuos question the effectiveness of this. They'd be to busy yelling at their kids, or talking on their phones. More then likely they just think it's falsing till they hit it anyway.

Good luck just the same.

what i would try is get one of those forward and reversing sensor kits and wire it up to some air horns that will do the front and the back.