You can make the layout size as needed in AC, and place borders for 2 sheets on it, or 4 sheets.. so you are basically making 2 sheets side by side and cutting that print in half (right?). In AC each layout would have 2 sheets.
I print C an D sheets off the same 24" roll (turn the drawing 90 for the size C sheet.. see screen shot). Your machine want except 24" wide rolls? There is no reason you can't have 2 versions of print files on one pln if needed, just name them accordingly and organize them via publisher. If you want size C sheets.. 18"x24" you can have each AC layout 36"x24" and place 2 intended sheets on it.