I agree with buzzcut1, campers should have a plate attached on outside rear, with serial number on it, and date of Mfgr. Number should appear on a decal inside one of the cabinets as well, with gross weight including options.
I imagine somewhere on the web that contains everything possible in the country, there exists a website where you can track stolen campers. That's a start, if the seller has no original Certificate of Origin. CoE comes from Mfgr with every new purchase - and should accompany every used camper when sold, altho many do not if it's been sold a few times.
