Try one of these numbers, these are off the list of suppliers for National. Like you, I had thought that Monaco purchased the molds. Someone had to. I understand that some of the National Techs went to work for Monaco, perhaps they could lead you to the Cap Mold. Good luck. Although your m/h is a 2008, have you tried looking for one in an RV wrecking yard with a good front cap?
Fiberglass / ABS / Molded
COMPOSITES ONE LLC
http://www.compositesone.com/product_info.htm
DUO-FORM PLASTICS (269) 663-8525
FRONTLINE MFG. INC. (574) 453-3149
KWIKEE PRODUCTS (800) 736-9961
LASALLE BRISTOL (574) 848-0080
NORTH AMERICAN COMPOSITES (800) 625-6220
REVCHEM PLASTICS, INC. (909) 877-8477
SPARTECH PLASTICS WEST (888) 721-4242
VALSPAR CORP. (800) 845-9061