There is also the option of US ARCH D (24" x 36") sheets, but not for Epson hot and cold pressed papers. Canson, Hahnemühle. Moab, and Museo supply some papers in this size. They are flat to start with, so no curl to deal with. They cut down to two 17" x 24" sheets with only two inches of waste. Or four 12" x 18", or two 12" x 36" sheets for panoramas.
There are also some papers available in A2, which is a better ratio for 3:2 images. But again, not Epson hot and cold pressed papers.
Brian A