/diy/ - Do It Yourself

so I've got a (16'x20') tarp that I want to put over this canopy as in the pic. I've done it this way before but the tarp wound up ripping eventually at the grommets (after a couple years). I got a better quality tarp this time (12mil thick versus probably 6 or 8).

I'm wondering if I were to sandwich the tarp between 2 boards (1-by's for instance) then anchor them by tying the boards via rope to the ground (as was previously done with the grommets) would it be more sturdy? I'd do this at the top of the tarp as well as the bottom.