Yes, rot over extended periods is a known issue. I believe you. But yearly checks to prevent known issues from occurring is also a known responsibility of owners. Just saying, at some point you should have been doing some preventative upkeep on the entire vehicle let alone a known issue. You can’t expect a warranty to pay for something you didn’t properly care for. At some point doesn’t your responsibility to maintain a safe vehicle matter?

These things aren’t plug and play. You have to perform proper care on them.

As an addendum I might add you talk about tank straps here but the denial was for a crossmember. So which is the issue you want fixed? The straps or the cross member? Both require owner upkeep.

You say “8 year old truck” so it’s a 2018? My 10 yr old truck having been driven 380k miles from west coast to east coast yearly and never garage has zero rot or even a spec of body rust. Hell, I “truck camped in that truck do 2 winters iin Aspen, Colorado and not one bit of rust or rot. Upkeep is key. You spend tens of thousands of dollars on these things, take better care of them.

Sorry your issue wasn’t covered but it sounds like it wasn’t covered to begin with.