Art:

I use an AN2551 receptacle mounted in the nose wheel wheel.  It is accessible whenever the gear is down.  No need to fool with  access doors.    Aircraft Spruce sells everything. but it is very easy to make your own jumper cables and save a few $$$$. I use 2 welding cables (20 ft long)  for jump starting/ battery changing.  Welding cable (surplus store ) has extra fine stranding which makes the cable reasonably flexible and exceptionally durable..  I installed a relay wired to the master switch so I can leave the cable plugged in whenever the aircraft is in the hanger.  Whenever I want to charge or jump start, just turn the master switch on.  Simple - almost foolproof.
Happy Building.  Bill Hogarty