I used one of the switched circuits on the Eastern Beaver PC8 wired to A First Gear standard COAX Panel fitting in this manner. Note the flip-top sticking up on the left side mounted through the Air-tunnel baffle. I have ridden in heavy rain and had no problems with it, and it seals quite well when nothing is plugged in.
GL1800A, KLR 650, ATAS, 1972 CT2 Cessna Skylane
Fly low, fly high, but fly!