Plopping suitable for overnight drying? Well I have personally never heard of that.
Most of us CAN'T plop longer than 15-20 minutes. If I plop any longer than that my hair is exactly like you described - soggy and deformed. They'll be limp and take longer to dry. I don't know the exact cause but it seems to be because the cloth gets saturated with water. I have found that re-plopping with a DIFFERENT, dry cloth after 15 minutes works perfect. If I'd keep on refreshing the cloth every 15 minutes I could theoretically plop forever.
You could dry overnight with nothing on your head, just lie your hair down on your pillow
some of us do that.