Ah yes, I remember seeing that Joe. That's an excellent idea.
I was thinking more of way to use it like you made your silver bath in the darkbox (below the bottom). I attached a quick sketch of what I had in mind. It could be a box with three baths in it. That box could be 'dropped' in the bottom of the darkbox like you did your silver bath. The silver bath would have a lid on it to keep it light tight.
I would rinse in the helper tray, remove plate and put it on a dipper and place in bath one with agitation then bath two, bring out and fix (I guess I could keep it on that same dipper). Maybe have the fixer with two rinse baths as well in a box. Easy to transport also.