I have some trays for 32x40 inch prints. The trays are about 34.5x42.5 inches. They weren't cheap (about $125 each, when buying 6 at a time), but they work better than my old roll 'em method. Roll 'em works fine for RC, but is much more difficult with fiber. I also do some which are about 21x58 inches. I have no problem rolling them, even in fiber.
Emil- I'm still working on getting my liquid emulsion right, but the goal is very large prints.