Pardon my ignorance, but what happens when you walk up to the car and you aren't planning on driving (say you need to grab something from the trunk)? Wouldn't proximity fire up the computer in this case? Also, doesn't it seem like a slight safety concern to have the doors unlock when you approach? Just thinking out loud I guess.
Also, I've had good luck with Kinetik batteries. I've had an extra battery in my trunk (Kinetik HC2400) helping power my stereo for about a year and half now with no issues. I'm also not running an isolator of any sort for what it's worth.