Hopefully, I won't offend anyone with this post, but here's what I do to keep the wipers off the windshield when the coach is stored.
I use two rather large pop rivets through the holes in the wiper arms. Lift the arms and slip the nail-end of the rivet in place to position the arm to hold the blade off the windshield. If you forget to remove the rivet prior to driving away, the rivet will stay in place. I use these when installing the sun screens over the windshield and under the wiper blades. The rivets hold the blades away from the windshield making it much easier to install the sun screen without the chance of breaking a wiper arm (very expensive to replace).
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The rivets are long enough to go all the way through the arm (about 1 1.4 inch) and the rivet end is long enough for a good grip.