For those of you who run your shorty pack foward here's a tip. I use 3M thin double sided tape. You can get it at your local office supply store or craft store. It's used for scrapbooking.
There are two kinds, removable and permanent. They both come with a yellow label. The permanent is marked with red and the removable blue. I attached a pic of the permanent. I use the removable type.
I put a strip on the bottom of the pack and then put it in position in the car. Stays put even with hard hits and peels off easy. If your careful you can remove the battery a few times and it will stick back in place. Handy when you're trying weight bias adjustments.