Knee boards
Steve,
Do not let anyone take the mickey out of you for what is a very good idea. You do what suits you and what helps you fly comfortably and well. Double bluff the posers. I have flown much of my career with useful pockets and they are a great idea.
I did teach aerobatics to a chap in a firefly who had cut a section out of a fabric softener bottle which fitted his leg perfectly when some elastic was added. He tied a chinograph pencil on to write with. It was an excelent idea which worked very well.
Flying is not about fasion, it is about enjoyment and standards. If you can not find the trousers then get some flying suit style pockets sown onto some normal trousers.
Great idea and enjoy your flying.
MM