"My question is does the Propex have to be mounted with the intake and exhaust exiting the sheet metal of the van"

Yes, the hoses must live outside the van, must NOT live inside. Also, leave the lengths of the SS hoses alone, do not cut them shorter for installation convenience. I think Frank Condelli mounts them where Loren suggested, in the small cabinet at the floor next to the bench. Also, I think it was Mark Drillock mounted a 2800 just behind the psgr seat against the base covered by a cabinet he made. That's an ideal location for immediate heat delivery as the duct faces rearward where most of us habit on cold mornings. Those locations are also fairly easy to route the intake/exhaust hoses through the floor to outside. 

Bob

Sent from DAS4X4