As someone who has only used a circular saw and a straight edge to cut sheet goods these saws seemed like a great tool. I have had the saw "wander" from the straight edge on occasion.
Hi Deb:
stop and think a minute, what does the track saw do? It ties the saw/router to a straight edge. Ok, duplicate that. You've already got all of the parts, with a little imagination and scrap, you can easily duplicate the actions.
Take your straight edge and make a cleat that goes over the top of it. The grain of the cleat should be at right angles to the grain of the straight edge. Now, take a good look at the plate of your circular saw. You'll find lots of holes. Use a few of them to attach the saw to the cleat. If there are no suitable holes, look carefully at the sole plate of your saw and you'll see it was stamped or molded. Look where you might drill two holes, one at each end of the plate, away from the motor or adjustment methods. Now, make sure you do not drill through any of the bends or ridges molded into the plate. I would think the outside leading corner and the inside trailing corner should be adequate to hold it securely. Make sure there's a little bit of play.
Now, the only tricky part...
Make sure you've got a really good blade installed! Circular saws go through hell and the blade takes most of the punishment. However, notice that track saws have a fancy cover over the blade. Make sure you have a second circular saw for the "dirty" work.
The _blade_ has to be set perfectly parallel to the sliding edge of the cleat that rubs against the straight part of your straight edge. I found that a digital micrometer, clamps and patience are the only way. Once you've found that "sweet spot" bolt your saw to the cleat in some way. If you have to attach a platform to the cleat and the saw sits on the platform, use a bit of plastic laminate or UHMW on the sole of the platform.
Now, I tried all of this and instead, made a saw specific straight edge.
One of the reasons that I'm interested in Jim's table setup is that, like you, my arms aren't long enough nor my pockets deep enough for another solution. I found that a few 2x4s on the floor and kneeling on the panel and cutting like that is the most effective way. Jim's table looks like an attractive alternative to the shop floor (when I can find the shop floor ;-)
See Below