Here is an easy way to add a velcro patch panel to your Co-Pilot bag.
That's cool! Does it flap around when you move?
Actually not. But, if you want to "fix" it in place, you can put one magnet inside the patch panel and one inside the bag. It will be very well fixed.
Some updates here:
This panel could handle a lot of things attached with velcro like tools pockets, water bottle pockets etc. Anything with a right size to fit the place on the side of this bag.
Color comes with my apartment, so I don't know the name or catalog tag, sorry. B&W picture is an aerial photo of Paris after WW2.