We have a 2012 Navion iQ that we have travelled from Windsor, Ontario to Palo Alto, California, where we presently are. We have also downsized from a 35 ft. class A (Bounder) MH and have found storage space to be a bit of a concern. We choose the Navion iQ over the other Navions because of the Queensized bed that pushes out in the rear of the MH and for the fact that it was more aerodynamic than the Navions and Winnebago Views with the bunk over the cab. We have not used the inflatable bed on fold out sofa, but find the pedestal table to be wobbly and , overal, a nuisance to use. (When we return home, there will be some plans to remove the "sofabed" entirely and a small dinette constructed in its place. -Since only my wife and I use the MH, we would prefer a permanent dinette with storage under the seat cushions.)
For external storage we have installed a trailer hitch cargo carrier basket and mounted a large lockable "Tuff Storage" box. We keep a diesel fuel (yellow) container, extra 30 amp electrical cable, water hoses, toolbox and two tripod stabilisers in it.. The small storage area under the bed is used for two lawn chairs, laundry bag(s), auto safety kit and other small items.
All in all, we are pleased with the Navion and the 6 cylinder diesel engine. Over approximately 3200 miles, we have a rough estimate of 15 miles per gallon compared to the 6 or 7 mpg we got on the class A MH.
We have purchased a Scan Guage from Auto Zone in California and I will be monitoring the mileage closely on our return trip.
The only caveat of the diesel engine other than the fact that diesel fuel is more expensive than gasoline, is that not all stations have diesel fuel as we discovered after pulling in to fuel up.
We will be doing much more camping and exploring with this MH because of the ease of handling on two lane roads which we were hesitant to travel with the class A.