Is there a way to matte out the green in this foreground without rotobrushing the entire clip?
First, yes I know she should not have worn that shirt, but that was not an option that day (she didn't have anything else and forgot she wasn't supposed to wear green), so let's move on from that. Second, as I mentioned, I know that I could just rotobrush this, but I have quite a few minutes of footage and it's 1080p, so that would take forever to brush it, freeze it and render it. And I'm finding that the area where her hair meets the green trim on her shirt on her shoulders is having to be adjusted every single frame. Any suggestions would be greatly helpful.
Your options are pretty much rotobrushing, or reshooting. You might be able to do a little with the foreground using Keylight's controls, but I can't imagine it would end up usable. (And I've fixed some very poorly lit, rushed green screen footage before!)
On the shoot day, she should have been sent out to get a new shirt, directed to wear a jacket, or swapped to a blue screen if possible. There's really no quick way to come back from this. Your best option is to reshoot and do it right, before getting to the edit suite.