I had a 300TE with the same problem, so I know exactly what you are talking about.
I have heard that a product called "Shoe-Goo" works well to reattach the vinyl skin. You must "clamp" the vinyl in place after applying the Shoe-Goo with clothespins while the glue sets up.
I heard this "solution" about a month after I sold the wagon, so I don't know if it works, but it does sound reasonable.
Good Luck and let us know how it goes.