Good luck with the Velcro. I've had problems with the part mounted
to
the cockpit wall sliding (sliming the wall with gooey) in the heat.
The 3M mushroom lock is stronger and works better the Velcro for
mounting heavier loads (sold at McMaster-Carr)

On your velcro, buy the non adhesive backed kind. Epoxy (or pliobond
or industrial contact cement, or...) the soft side to your cockpit
wall and use upholstery needle/thread to attach the spiky side to your
to your pockets (glue bond the spiky side to solid objects). When I
ever want velcro to stay put on any surface, I use the strongest
bonding/fastening methods I can, because in some conditions (heat
etc) the hook and loop is invariably stronger than the bond you can
achieve with the sticky back crap they supply it with, which will lead
to the same problem Frank had.

Your bond has to repeatedly win the tug-o-war with the velcro, so that
rules out the stock sticky in my book.

-Paul