You could put your developer tray inside a paper safe!
I once did something similar to stand development while I was printing. I was working with a badly overexposed negative. Due to the overexposure, it had extremely low contrast. I couldn't get anything resembling a decent print from it. I made one last try. I exposed the paper, put it in the developer -- and the phone rang. I left the darkroom and answered it. After about twenty minutes, I went back in. The print was perfect!