Repairing Interior-exterior wall in Jayco Question

Thanks for the responses. If it had been me that this happened to, I definitely would have returned the rv. But my bil was in dire need of a place to live so he got what he paid for.

I will go with framing to the deck once I replace any floor joists in need of repair and then glue to exterior from interior side. I will be sure to take pictures of before, during and after, and post here.

Thanks again,
John