Winnebago had a serious issue with the steel frame behind the windshield rusting badly, which will first cause leaks then will eventually crack the windshield. You can try resealing around the glass but, if you see rust when you remove that rubber trim, the only way to fix the problem is to have the glass removed, the rust dealt with, and windshield installed with new sealer.
Hopefully, your leak is marker lights. Deal with them first and hope that takes care of it.
2019 Grand Design Solitude 384GK 5th wheel. Glen Allen, VA