Whats the rheostat?
Cigarette lighter and radio have a constant power supply
I found one key on supply off the ign switch. Its a small wire though. It may not be able to supply much current (could be the main supply wire for a relay etc) I would prefer not to use it.
Heater fan is key on and nice big fat wire but its not in the best location.
What a PITA, they could make it easier!