Well, one way of coping with large prints is to make a table of the trays and have no gaps between them, as per Clyde Butcher - seen in this video http://clydebutcher.com/technical-info.cfm
Alternatively, how about trough developing, where you make a scroll of the paper and keep it moving through the chemicals? I think you would need two pairs of hands for 40" paper though, especially fibre.
With the single tray method, it is heavy and trays are not always rigid. I have often thought of putting a hinged table-top on the bench. In that way the corner of the (huge) tray points at the hinged edge and you lift the opposite end of the table to drain most of the liquid, at which point it will be light enough to finish off by hand lifting. Using siphons and stuff just seems to over complicate a simple technique (and slow it down).
Large, or odd-sized, trays can also be made of fibreglass over marine-plywood, as described many times in Apug. I have never done that, but maybe getting the right sort of resin would be critical? The rigidity problem would be taken care of by my hinged table-top idea (maybe I should patent it?).
When you are setup make a few photos and stick them up in the darkroom picture sticky-thread.