I did this on one of the F-86D's I built. Long time ago! I think it was a male/female Dean's connector, the male end was recessed into the side of the fuselage so that the female end from the power source would plug right into the fuselage, very clean and cool because my battery was built into a model of the ground power unit the full size 86's used. The wiring from the airplane side had a tiny alligator clip which went on the glo-plug and the ground wired to a mounting bolt. An RCA jack will work but they are big and will need a good solid mount

Thanks Russell, that's the one! Or actually, those are them!

Had dinner in Klamath Falls once on the way home from a FF contest in Oregon. Pretty town. Probably lots of good fishing and hunting in the area.