Hi Weshawkins,
I'm sorry you're having this problem. And I'm sure it's especially frustrating given that you've covered the trailer to protect it from the elements. We've had many past discussions on the forum over what Heartland Owners have experienced after warranty expires. Perhaps a recap might be helpful.
First of all, the bad news: during the warranty period, Heartland is obligated to fix problems, but afterward, they are not. The warranty covers all types of defects; minor and major. Even though many owners think there ought to be, there is no such thing as a longer warranty for more serious problems.
The good news: as many of us have found, Heartland often does make post-warranty accommodations to maintain goodwill. The vast majority of Heartland owners participating on this forum would agree that this is the case. Sadly, there are also a few owners who have been left dissatisfied.
Second, from my interpretation of prior posts, the likelihood of an accommodation often seems to depend on what the experts at Heartland think may have caused the problem. If they think it was caused by a materials problem, or a manufacturing error, and the problem is significant, my observation is that they usually take care of it. Some people have received help even several years after the warranty has expired. On the other hand, if they think the problem is due to a maintenance problem, my observation is that they're much, much less likely to help. I don't have any inside information on this; I'm just giving you my opinion based on reading many owner posts over the past couple of years.
So, knowing that Heartland will often make a post-warranty accommodation (even though they don't have to), and that they're more likely to do so when the problem was caused by a manufacturing defect, let me suggest that you contact Customer Service to try one more time.
I would suggest you ask what their experts think caused the problem. If the rep tells you he's not sure, ask if someone more familiar with this type of damage is available. You need to make sure that someone who knows the difference between manufacturing defects and maintenance issues has taken a close look at the pictures and has provided an expert opinion. Sometimes they will ask you to get the dealer to render an opinion after inspecting the damage.
If the experts think it's caused by a maintenance issue, you might ask them to comment on how this might have occurred given that you cover the trailer.
If they agree that it looks like it was caused by a materials problem or manufacturing defect, perhaps they'll change their mind and offer an accommodation in part or whole. If not, you might discuss that you've read where many times Heartland has helped out-of-warranty customers with this type of problem, and ask if there's a reason they wouldn't do the same for you.
I hope you find this helpful and I hope you're able to reach some agreement with Heartland, or if not, at least get a better understanding of how this happened and how to prevent additional damage.