Pleasure Way and Leisure Travel B rear sofa can be made into a twin or queen.
Non of these are really a king.
Big difference is location of the galley, on the passenger side.
Rd Trek and Airstream galley on drivers side.
If looking for a twin bed configuration check out LT Unity twin bed B+.
That is the one I would probably move to.
All these manufactures use the the Sprinter chassis.
Mileage on our B, Pleasue Way Plateau TS is 18 to 20 mpg, if you move to the B+ mileage drops to about 15 to 16 based on our friends just returning home to Alaska.