Can't reply to old threads these days.
There were a couple new/prototype RV chassis shown at the RVIA show last fall. There was the "American Power Chassis" from Jones and Sons and the "Extol" and "Revel" from Spartan. An 8.8 liter aftermarket version of the Chevy 8.1 was mentioned as a possible powerplant.
Spring 2013 came and went. Anyone heard any news? Google doesn't seem to turn up much...