I have a 750 x carve in a sound proof box and wanted to carve a sign 40" long. I found tiling on this web site but because of my box I could only extend out the front door. Here is how I did it. I went into easel and created the sign. First, centered it on the wood. Then divided the sign into half trying to have the center line between text. Copy the file and save it. Highlight the top half and set the depth to .030" outside cut. Highlight the lower half and set the depth to zero. Go the original file and do the opposite. Then select all, flip the text horizontally and vertically. I then cut up some cardboard the size of the wood and taped it to the waste board. Draw a line across the half way point and place it on the waste board zero line. Attach your pen attachment to the router and draw the sign, first the top half then turn the cardboard around and draw the bottom half. Ensure all the text lines up, adjust as required. Now remove the cardboard and install the wood. I had a piece of cedar 3" x 12" x 40" long. It worked out great. Now I have to figure out how to attach my pics.
When there is a will there is a way.
You were pushing you limits with that thick stock and original Y risers.