Peter Duniho wrote:

I'm still wondering where one might find any 5"x7" signal mirror,
crashworthy or otherwise.

Survival Tech's ST-1450 kit contains a 5x7" "signal mirror", but AVWeb didn't
think much of it. They said it was a mis-labeled camping mirror.

The OP could have simply misread an ad somewhere. The 3x5" mirrors are
advertised in many places as being 5x7cm.

The largest signal mirror I found in my search was 4" x 5".

George Patterson
Drink is the curse of the land. It makes you quarrel with your neighbor.
It makes you shoot at your landlord. And it makes you miss him.