Posted for Bill Hogarty <billhogarty@direcway.com>:

Clark:

I used the same aux power inlet recommended by Dave Saylor except that I mounted it down low on the firewall facing down so that I only had to cut a small piece out of the lower cowling for access.  Simple, effective, and out of sight.  Bill Hogarty(yes, I copied the idea from someone else)
P.S.  I wired it directly to a continuous duty 12 Volt relay so that the aux power would activate the relay.  Nice feature in the event you ever have a completely dead battery.