[Mikendebbie]

To deepen the mystery for how a crack might develop in that location - I sketched in the theoretical aluminum tube framing for your sidewall. This is based on looking at the two screenshots below from the youtube video "Keystone wall construction". I don't know what it looks like exactly - but it would be something like this. The luan plywood-backed fiberglass panel is vacuum laminated across several studs in that area. Seems that a stress crack would be difficult to form in that location. I agree with the idea expressed above that sometime in your RVs past - maybe the nose was lightly impacted by a shortbed truck cab. It was not a sudden impact - but more of a slight push against the cab over a few seconds while backing into a tight site. The fiberglass cracked - but was not noticed until you guys started working on the finish years later - which in itself is hard to imagine.