I don't know whether the duct tape really helps stop the fabric from tearing... mine have never torn. But I can't prove that it's because I used duct tape. It seems reasonable that it would offer some reinforcement, though. It's been kind of a trial and error process for me...
Apply for a patent before the left steals it.
You might want to add stapling the edges of the duct tape to reinforce the tape to sheet adhesion.
Also, use a hole punch, a single hole punch like what you can get at staples to make the hole for the tie wrap.
A clean hole will rip much less easy than something that is vertical or horizontal because of the way the sheet is woven. So, the hole cutter, a hole punch sounds best.
That sign-method was a great idea, you should patent it!