Welcome to iRV2.
Sorry your first post is about problems .
I hate to say it , but your problem maybe deeper that the rubber windshield gasket .
The windshield should have less than 1/4 " of space between the glass and the mounting grove in the rubber , and most times the glass is in the rubber without adhesives or sealants.
I'm not familiar with your year and model of coach , is the front cap fiberglass or metal ?
The windshield mounting rubber , fits over a ridge on the coach front cap , then the glass grove is rolled open , the glass installed , and the round " lock strip " is worked into a cavity on the outside of the rubber to force the rubber tight to the glass.
If you have a lot of movement in the glass the ridge on the cap maybe damaged.
Any chance you could post a picture of the problem?
If the glass has shifted enough to open up a hole between the glass and the rubber , repair is a job for a shop .