The tubs are clear, I may try using them and putting them in the dark or a solid bin or finding some the same size or there about. I could tape them up to make them opaque or do something like that.

I was thinking the 2 smaller bins in a large one would make the temperature equal throughout the smaller ones but that doesn't like it would be a problem.

As for Duct tape, I would think that would make it easier, don't I need a clear slick tape around the rim to prevent them climbing too high? Or is there a clear slick duct tape out there?