Since we don't have an audio section...

A instrument voltage regulator provides sufficient amperage ?

It's not a factory style, it's a 1 amp 5 volt that I built for the guages when I was using the factory ones.

But to answer your question, yes the one I used is a 1 amp and that is the recommended minimum charging amps for the Kindle.
It will be connected to the car most of the time so I don't need it to quick charge.