What you need is two pieces of 4 ft long, straight, 1x1.5 inch stock, a couple of short pieces of thin stock to use as stop blocks and a couple of small clamps to hold the stop blocks.
Measure and mark the width you want to cut and set up the track to cut that line. Lay the first stick so it touches the track and clamp the stop block on, under the stick so it is snug against the edge of the sheet. Flip the clamped stick over and lay the second stick on top so it touches the stop block. Clamp the second stop block on so it touches the open end of the first stick (see illustration below-stop blocks are red). Now you have two exact length sticks you can use to make both ends of the track perfectly parallel to the cutoff edge.
This will give you repeatable cuts on full sheets of flat stock. If you're breaking down the sheet into several different size pieces, you repeat this measure, set stop block(s), line up and cut process for each new piece. The advantage of this is the no matter what size you cut, the cut-line will be parallel to the cutoff edge. And you get repeatability if you're making the same cuts on several sheets of ply, for example, making a set of same size cabinets.
I was thinking you could adhere a tape rule to the sticks, but I don't think that would be very helpful compared to careful setting of stop blocks. The important measurement is the width of the cutoff marked at least top and bottom to set the track. Setting the first stop block assures that the second will be identical, thus the cut will be perfectly parallel to the edge.
If you want, you can send me $400 and I'll send you some sticks, clamps and stop blocks. Heck, I'll even paint them red and silver for ya.