Touring - flip-up sign to remind us that bikes are on top

Yakima used to make a magnetized sign that you'd put on the hood and that would flip up when you slow down, to remind you that you've got bikes on top of the car. They don't seem to make it any more. Does anyone know where to get something like this? (A sign on the rear view mirror doesn't seem as useful -- you just get used to it and then forget and crash the bikes ...)

How about this: When you put your bikes on the roof, put the remote in the trunk or leave it in the house. That way you have to stop and get out of the car to open the garage and should remind you to remove the bikes first.

You could also set another bike or the lawn mower in the middle of the garage so you have to move the obstacle before parking.

just about any vinyl sign place has magnetized vinyl that they use to make
fridge magnets. comes in sheets 2' x 4' or so, just about any color. i used
a couple plain white sheets to cover the door markings on my company truck
when used off duty. would at least give you something on the hood. would
it be legal to wire up some led blinking lights to your brakes, mounted on the
dash?

I saw somebody suggest putting a mirror above your garage door, angled so you'll see the bike(s) on top of your car as you approach.