I guess you could do this but if it was so much of a problem why not just use your camera phone? All the same it is a good idea but there are many other devices you could use to do the same thing.

Or you could write the level & color on a scrap of paper and put it in your moneyclip. . .

But, you don't always carry a camera or paper.

But, you don't always carry a camera or paper.

I always have a pad of paper & a pen in the car.

I always have my camera phone but you might find a market in the oldest of the baby boomer generation.

Increase the range of keyring car lock remotes so that you can hear your horn talk back to you. Though in parking structures the sound of a horn won't help much to know which level you are on unless you just stick your head out of the elevator on each level and listen for the horn.

Lots of people have camera equipped cell phones. They can use their cell phone to do exactly that, if they remember to do so.