You really should not change the loading of any circuit on the switch at all as that may effect the operation of systems downstream because of possible voltage drops...which CFM is well known for. Depending on the load, you should use the fused and keyed accessory circuit to either power the light or as a relay trigger with a separate fused battery power supply. The accessory plug in the dash is the end of that circuit. You can easily get to it by removing the front storage tray to tap into. If you will tell us how may watts your light is we can help you decide which way to go and how to do it.