Editing my response after seeing DWscots post while I was keying mine. I also agree with his suggestion! There are different ways to skin a cat!
My 2002 IQ Villager) CC came with a reducer, that being a wire wound ecpasulated resistor that drops the voltage of two of the batteries from 16 to 12Vdc. It is located in series between the (-) terminal on battery 6 and the OBC. The lights and horn were wired to the terminal block on the back side of the OBC (-) (after where the lead goes through the OBC) and the positive terminal of battery #5. Not only did it serve as power for the lights and horn, it also kept the OBC "awake" by the very small amount of current it draws when everything thing is turned off. If yours is the same as my 2002 IQ, you can see it mounted on the inside of the aluminum frame that runs fore and aft behind driver just behind battery # 6. The lights and horn draws power from the two batteries which means that they will run-down a bit before the other 4. However, the charger system is suppose to go into an equalize mode when needed (+ almost 60Vdc at about 5 amps) for 30 minutes or sometimes a hour which is suppose to bring all batteries to full charge (controlled by the OBC turning off the charger's voltage regulation). Note that he reducer will not provide enough current, at proper voltage, for radio operation. For that you would need to disconnect the wire-wound and add a parallel 48V to 12V converter/reducer between the (+) 48Vdc terminal (pos) battery #1 and the (-) terminal block on the back side of the OBC where the old reducer (-) was connected.
The cc wiring diagrams found on this and other forums did not show the lights and hron wiring, nor the reducer.