There are many organizations doing this now. I have seen it all over the vehicles.
A simple FR on the bumper of a vehicle will only tell other FR people who we are and identify a friendly.
If you don't do this, I will.
The numbers are pretty simple. About a buck for the sticker. $2 for FR and $2 for you. Simple. For $5.00 everyone wins.
Of course, I would check with JR before I would do anything and get permission.
FR people have thousands of cars running around. Would it be neat to see an FR in an oval and honk the horn.
I'm one of those visual learner types!