Jason,

... when you have the innertube hooked with your thumb, use the other fingers to push the light out of the innertube instead of pulling the innertube down. I found that to be faster.

To stow the backup light I do:
1. Hook it to your d-ring.
2. Slide the thumb down the harness until you hit the innertube.
3. Lift the innertube and put the backup light in with the other hand.