The cost of professional replacement of a rear panel will be in $1000's. No doubt. Your coach looks relatively new (or newer). Insurance won't declare it a complete loss unless the cost to repair exceeds its current market value. If it's just a rear panel replacement, I'd suspect it would be repaired.
Here's a thread I found on the same issue:
http://www.keystoneforums.com/forums...ad.php?t=23394