I know if you buy a Cruise Craft here, it comes on a Dunbier Trailer. No matter what, or when the boat was built, it is not your fault that the trailer isn't compatable to the weight. If the dealer stuffed up, which is what it sounds like, then they wear the extra costs, if Cruise Craft stuffed up, (which I doubt it, as all dealers have different agreements with trailers, same as they do outboard makes), then Cruise Craft should be picking up the bill.
There is no way that this should be coming out of your pocket, as you agreed on a price and a supposedly legal package, no extra costs should be coming from you.
I agree with Banshee, the deal is done, this is your boat, you shouldn't have to wait for another from another dealer, but if all turns to custard, and they won't come to the party, then I would tell them to stick it and go somewhere else. Not only for dollars, but the principle behind it.
Interested to see how things go,
Corry