The pen issue again. If you use a fine, permanent OHP pen (basically a non water soluble felt tip) it will write on both. If you go to a good art shop, you can buy something called a "Staedtler Lumoplast", which is basically a very posh rubber. Then will rub out permanent felt tip from your laminated map. Problem solved.
Regarding cockpit ergonomics.
(1) Ergonomics that suit a wide range of pilots, from 5th percentile oriental female (now there's a thought), to 95th percentile Caucasian Male (which should keep Whirly happy as well). There are ergonomic tables for these, published by NASA, but they are rarely taken into account by light aircraft designers.
(2) See if you can get hold of a book called "Design for Flight Safety", by DB Thurston, ISBN 0-02-618501-6, and another called "The book of flight tests", by A Bramson, ISBN 1-85605-000-9. Both may be out of print, so inter-library loans is probably your best bet.
(3) If you can design a reasonably accurate and reliable fuel level gauge for light aircraft, you will earn the undying gratitude of millions.
(4) A CWP.
G