Theres plenty of airspace behind the light cluster when its back in the bumper, you can just have them on the back of that. I dont know much about electronics, but most of the LED bulbs I've had before had resistors in them and they never overheated. I appreciate that you have a lot more than a normal LED bulb, but you should be able to have something on the back of the cluster with maybe a heatsink. That will be easier than trying to find where in the control boxes the indicators are controlled from