I don't know, but someone might try to test the effectiveness of your new invention, possibly leading to a dent instead of a ding...

An alternative:
After doing a quick count of cars (roughly 100) driving around my area, I found only 1/4 of all cars had a passenger. This means that since every car has a driver and only 1/4 have passengers, you can lower your exposure to potential door dings by 80% by simply parking where there is not another parking spot to the passenger's side of your car. (ie, at the end of a parking row, next to a bush, parallel parking, etc. as compared to a parking spot between two others).