Hook up a relay to a distribution block. The relay will have a remote wire that turns it off when the key is off.
So something like this ? http://www.motorcycleinnovations.ca/Rowe_PDM60_p/pdm60.htm
This one seems to have a cable that hooks into the ignition already.
I have a friend in buffalo that I ship stuff to. Small group buy? 3-4 max.