I have a similar method of torquing....twist until it breaks or strips...then it must be tight! :lol: I stripped one of the trunk liner screws as well and just used a slightly larger sized coarse threaded / self tapping screw. If the fit is too tight, you may need to drill out the plastic posts they thread into so they don't split. These screws really don't see much stress and there are plenty of them. You could almost just dip the original screw in epoxy and slip it in the hole (may have to repeat each time the liner comes out).
Lots of good solutions given, I have used all three, Toothpick, larger screw, fill & tap. Tooth pick works great, as it gives easily, and will not allow for a lot of pressure on the screw hole sides.
Here is how you do it. You take your lovely wife out for dinner, Enjoy a great meal. Tell her how wonderful she is and how without her you would be a total dork. Then pay for your meal, pick up a couple of tooth picks (un scented...LOL) on your way out.
If she catches you fixing your bike with the tooth pick, just tell her " see, I told you I was a dork without you, and I stripped out this screw hole when you weren't with me". She is gonna LOVE YOU !
With out a question Mike that would be the best case senario, but I've had a couple of friends who had screws stripped in a number of areas right from the factory. Even found one of the nut plates stripped on the top shelter for Joe's bike. You know how those assembly plants are!