Dave, You'll have more answers and interest over in the Escapee's HDT Forum... RVNetwork.com
The is also a large presence on Facebook. Search HDT
But yes, you can run the Fiat lengthways. 280" wheelbase can be shortened depending on if you want to remain tandem axle or if you single the truck. Tandem you can stay shorter since you won't be transferring the weight as far forward. Is there a particular reason you want to stay in the 65' length. Could you go 67-69'? It opens your possibilities more.