I don't tie the ends to the clew. I use a system I've seen on a 49er.

Use double braided line, extract some core in the middle of your sheet sufficient to make a small loop. Work the cover back in place. You now have a loop of core outside of the cover. Make a cow hitch by feeding the loop in the clew and passing the two lose ends inside it.

Feed the lose end into the various blocks. Where they meet on the trampoline cut the excess cover and splice a tight loop on one side. To connect the two ends pass the lose end into the loop and make a stopper knot (49ers use a skiff knot, I hate those as they are hard to open so I use a figure of 8).