The EZ pass is strong enough to allow it in the windshield bag or anything that is not metal. They say put on windshield but not needed. Been running one for about 15 years and it is put away. Picks it up every time.
I just did a 400 mile roundtrip ride to Rolling Thunder with the E-Z pass attached to the windscreen using the velcro strips. No problems. It was hot and everything held tight.