regarding the the cheap option, I have done some 20x24's using a single tray. I use 4 litres of chemistry in the tray (so 4kgs) and a set of household buckets (about 9 litres I think) for each chemical (I use just use plain water for the stop). I use a higher dulution developer so the time it takes to empty the tray and rinse before getting the fixer in is less critical. Pouring the chems out of the tray into the bucket is fairly straightforward but not 'easy'. I doubt man-handling a 40" tray would be reliable and would require some mechanical assistance.