I bought a 4x8ft sheet of PVC that is used to laminate countertops. Cut out a rectangle with width of the shorter size of your paper and length about 3 inches longer than the long side. Roll it into a cylinder. Then glue the ends together. This is what I use to process large prints. I use a single tray which is a bit longer than the cylinder and fill it with developer. By the way, i put a 2x4 under one end of the tray to use less chemistry. I put the cylinder into the tray, roll the exposed sheet of paper from the enlarger and put this photo roll into the cylinder. Then I start slowly rotating the PVC cylinder and unrolling the photo into it while entering the developer. When you unroll the whole paper, it sticks to the PVC cylinder by capillary effect (it sticks like glue). From that point on, the process is obvious: develop, take the whole cylinder out, dump the developer from the tray and refill with the next chemical. I also do a few washes in that same cylinder before pulling the photo out. This way I don't touch the photo and handling is very easy. The biggest print I've done so far is 20x30, but you can go as wide as you dare.

I hope it clear, if you need photos, I can make them next time I'm doing a large print.

Eugene.