Just read your post. I'll definetly be incorporating some of the features you mentioned with regard to the darkroom at Yosemite. Not sure I'll have that much space, but I won't be too cramped either. There exists a window in the space and I'm going to try and incorporate it as a fast way to evacuate fumes. In addition I'll have a vent fan for when the window is light tight. I've seen some industrial rubber flooring that has raised circurlar pads (size of half dollar), I'm going to try and get some of that if I can afford it.