I am not sure about the dual range power coming out of the ballast. If so, I am not aware of any but traditionally, the output of the ballast is normally a specific load only. HIDs run hot just like Halogens but you should be able to get away with LEDs and they normally run cooler. I have good luck with Morimoto HID bulbs. A little less expensive compare to a Phillips and I can't tell the difference. If you haven't noticed by now, I am a little nutty about lights, all kinds of lighting from flashlights to home lighting to lighting up your yard.
Check out The Retrofit Source. They should help you with a quality set up.
https://www.theretrofitsource.com/
Yeah, the Cayman is too much fun. Its almost my daily driver is I don't have to drive my truck. I bought a couple more cars since we talked. Hope you are having too much fun with that boat.