I like the idea of adding a timer and something that shows how many kills you got, but I'm gonna have to disagree with the fact that "fort killers are fine how they are." Why can't players heal? This allows for more strategic play like taking over a certain part of the base with gang members, and holding the position instead of going in base, spam, die, repeat.
I also don't see why gangs that are holding the base can't participate in the fort.