What about rolling the sides in, as quilters (like me) do when starting to quilt a piece too large for the machine. I roll up the side and use old fashioned bicycle clips to hold the roll of spare fabric out of the way. Fabric and quilt shops sell them - they sort of look like a slightly squashed circle, whose ends meet but aren't joined - the ends are usually folded back. The metal is flexible, about 1/2-3/4" flat piece - meant to hold your pants leg up so it doesn't get caught in the chain....
I bet that would work. It's better than using big binder clips.
No advice, but I like using the rug mesh for teaching anything really complicated - like to show needleweaving. Or intricate filling stitches. It's big enough to weave with NP weight yarn, and the students can see it clearly, and I'm not stumbling doing it - or so I like to think.
Ellice