Good Morning, Jerold,
Very occasionally on E-Bay, a comercially-made drum originally intended for processing 20 x 24 inch color prints will be listed. If not, I'd suggest buying a length of plastic tubing around 10 inches in diameter, gluing a solid piece of plastic across one end and a similar piece with a 5-inch centered hole (for pouring, draining, and inserting the paper) across the other. It won't be light-tight, of course, so process under safelight through the fixer step.
The drum approach works quite well. I have a 16 x 20 Chromega drum and have largely given up tray processing in that size. Years ago, I made a drum similar to that described above and used it to process prints which were about 40 inches wide; I made an accompanying platform with four plastic furniture casters mounted wheels-upright and rotated the drum manually. It's a little awkward and a little messy, but it's a lot more practical than dealing with super-large trays.
Steve's suggestion about wallpaper trays also sounds like a good one. I bought a set of those about thirty years ago intending to try that approach, but never actually did. Maybe someday. . .
Konical