Check these babies out. They fit on the bottom of your hard bags in the grooves that are interdispersed over the rails the bags sit on. You can either get them empty and put your own tools or buy with tools already in them to include CO2 cartridges. They take no extra space.

https://www.storagepouches.com/#!__online-store

I checked those out - great idea for stuff you bring and are never going to need - I mean they are berried under everything in your saddle bag. The only problem with that strategy is when you do need to get to whatever is in there, - how much do you need to unpack to get to them?
I took some 3/4" foam padding and cut it to size, laid it into the bottoms of my saddle bags and then covered it with a towel. When I'm traveling light it keeps the contents from getting damaged when bouncing around in the bag. And when I'm loaded it helps keep the beer cold.

Yes but a selling point is they are there, they are out of the way and not taking up space and regardless you have to dig for them its better to have and not need then to need and not have.

Cool stuff. Got a set on the way.

I couldn't agree more - when traveling - if it fits and you might need it - bring it.