Yea the quickest way to trace the HL is just to unscrew the top hull connector and look at the back of the small pcb board and follow the traces to see which wires have the LED power going to it. Then tap them near the plug at the bottom. I might actually be able to make something up for you. We will talk soon.
Also yes it is quite easy to turn on LED lights with a RC remote. There are controllers for it as well, allowing lots of multiple options like blinking headlights, bright, dim, etc. RC car light systems are a cheap easy way to do that. Some of the good ones will apply brake lights when there is no throttle and turn them off while there is throttle. Then there are ones that apply a blinker when you turn as well It would be pretty easy to mod one of these for another project. Just search around for RC LED controller and you will be surprised.