I've had the PennState jig for several years and would do it again. I
pull 4X8 from pickup onto stands, clamp the alum guide and grab the
circular saw.


There are other suppliers of straight edge guides which have the tool
ride on a plate instead of against the edge. Those that I have seen in
catalogs do use clamps. One supplier is Penn State Industries. I
cannot speak at all to the quality of their product as I have never seen
it but it seems to meet your description. I suspect it is a lot less
expensive than any tool from Fein.
John