Christopher,
You are best off getting legal advice and if the caravan is under finance get the finance company involved, I've a similar problem on a 2006 model van that use only used for four weekends during 2006. During its first service in Jan 07 they found cracks in the front panel. At first I was accused of cracking the caravan by towing it, but the dealer soon backed down with the production of an independent professional report and then proceeded to said that the cracks are a manufacturing defect.
I have been pushing for a rejection or replacement of the caravan myself and from the internal notes by my Finance Company (now disclosed to me via legal means) they seem to be thinking along the same lines but the dealer is not playing ball. The dealer is saying that will not replace the caravan since there is no profit in them for it, because Bailey will only repair the caravan and not pay to replace the caravan themselves.
So now I'm about to have a court trial within the next four months to settle this matter, so far it has been a long hard road with no certain outcome forthcoming. The only good thing so far is that my home insurance legal cover is paying the bills so they must think there is a good chance of a ruling in my favour since I understand that insurance companies do not like paying out if there is little or no chance of success.
Good Luck, Bill