Thanks for your thoughts! I like the RS232 idea and picked up a 9 pin to test - but I found it very difficult to get apart. It looks like they would work well installation-wise, but once plugged together they stick like mad - which obviously they were designed to do. I tried to flatten out the female flange so they would slide together and apart more easily, but made rather a mess of it. Any ideas?
I have the same problem with the Multiplex 6 pin plugs I'm told are used on many gliders etc. - but I could hardly get them apart period! Since the cabin is finished with 8 passenger seats, I don't want any wires hanging around so I only have the 1/2" of space above the cabin roof to play with!