I don't think you would have to worry about a male or female lab being aggressive in a peacock/hap tank. I have a quad of labs in mine and they even breed sometimes. the others don't pay them any attention.
I had 1 YL female in my 125g all male Peacock / Hap tank for almost a year and they didnt pay her any mind. Last month I added 3 more YL females that I took from my 55g, I was tired of them breeding, and they dont pay them any mind either. You should be fine.