Well, I agree with your previous comment about one thing - you must reflect on it; do you feel like you need another proofreader or not? Maybe discuss it with the one you have left too.
I don't think it would be a problem to recruit late in the project though. Some people can be pretty fast - as long as you tell beforehand that the project is well advanced, so they know they'll get a lot of work, it should be fine.
Haha, you saying you dislike writing bad endings made me chuckle a little. I actually love working on bad ends. For the very same reasons I love doing bad ends when playing. I like to see the bad outcomes so the good ones seem even happier to me. You know, like, being happy for the characters since they had such a beautiful ending because you know all the grim alternatives they've managed to escape