That age you won't get matching they change designs, but if not done already check with the caravan manufacturer they may supply the same or similar. They may also advise on fixing although don't see why not with contact adhesive but remember once on you can't move it so make sure it goe on right. Make sure the existing has dried thoroughly and has no buckles in it.
A suggestion is hardboard and the plastic coated washable wall paper.
Bob
April 2011