Using something like the LR32 positioning arms except longer to accommodate sheet stock.  It would attach to a guide rail.  Downside to this method is it would have to be removed before using the guiderail for cutting.  I'm a bit surprised Festool doesn't already have something like this.

It is not very difficult to make something yourself for repeat cuts. I dont generally do alot of narrow ripping with the TS saw and rail. I have a table saw for that. but for larger stock I have made something like bench hooks that hook the edge of the material and but the back of the guide rail. the length of the bench hooks is the dimension you want minus the width of the guide rail(my saw happens to cut exactly 185mm off the back edge of the rail.

Another way to this method would be to make an adjustable length bench hook with a notch that fit snuggly into the top slot on the rail. That way you wouldnt have to remove them before you cut. I didnt have to remove my bench hooks but they were not adjustable.