If I get my system in before you I will let you know how it works with a light weight battery. It's supposed to arrive today but I won't be able to start the install until after my last autocross of the season Dec 4-5. I'm currently running a Braille 2015 in my car and its been working good. I have to big fans and electric water pump and haven't had any issues. I don't have a stereo, heater or most of the interior lights so that could be helping. I do run a 130amp alternator in the car currently.
I'm going to have the Pro-M system control the fans and I might have it run the water pump but I will have to see about that. When I'm between runs I will sometimes turn off the engine and let the fans run with the water pump which helps cool the car down especially when it's really hot out.