Probably a real inconvenience but I would take it back to the factory for repairs if that serious. Sounds like BS stuff about bad batch. They probably changed procedures of application or using a cheaper brand that didn't quite work out to save money. Like I mentioned, all manufacturers are building cheaper. I have a friend that recently bought a Winnebago couple of years ago and not a happy camper. I've always bought new but cheap building is getting so bad we have to see an RV on the road a couple of years to see if it holds together before buying.
Frustrating for sure but eternabod tape if applied correctly is really good stuff. It sticks to almost anything. I used about 16' of sticknbond tape and about 6 tubes of self leveling Dicor on my roof already (fiberglass roof) over cracked caulking. Cost was about $150. A bad leak can cost much more than that. I inspect my roof 2 or 3 times a year for any cracks. BTW you need warm weather for application of those products.