When doing my ATPL I built a pen holder to fit onto my clipboard which was easier to use than the spring type. Much to the amusement of my fellow students, but it meant that I could store the pen with the lid off and grab it instantly to write something.
Later, when I was flying the Dash 8, which didn't have any altitude bugs (
) the company fitted some little 3 digit MDA reminder units to the glare shield that were plastic with a mechanical push button for each digit. An MDA reminder could be set fairly quickly, and by the look of it more easily than the rotary dial ones you've mentioned, but I don't know who made them, sorry.
For a couple of quid each, you could buy two small calculators from Staples and mount them somewhere suitable and it would be easy to punch in a heading and an altitude quickly?
They would double up as....erm calculators too !!