Sometimes it's possible to get an oversize sheet on an undersized platen letterpress. What is important to keep in mind is the distance between the arms on either side of the platen. As long as the sheet is smaller than that dimension, it could fit. This is a long 4 x 18 inch card that needs to fold in half to 4 x 9 inch and fit into a standard #10 envelope. We are set up in this photo to run a 3 point matrix score, but this works for printing as well. To fit this sheet size onto our 10 x 15 size C&P platen press required a special McGill gauge pin for the side guide that fits between the tympan bail and the side of the platen. It extends beyond the platen and adds the couple inches needed to get the sheet to land inside the working area. It is a good solution to handle smaller hand fed jobs.
These guides came with equipment we purchased several years ago and we can not find more. Although, it could be rigged up from hardware store material pretty easily. If anyone has a source for these guides, please share! Someday we'll just get a bigger hand fed press, but then there will be an even bigger sheet.