First everything was stripped from the chassis so that items could be moved to more suitable places ....  batteries moved lower to the ground, exhaust re-routed out the side instead of doubling back on itself and exiting via a stack at the rear of the drivers cab.
A standard cab\chassis truck uses the space under the tray very poorly because it doesn't really need to place much under there. Not so with an off-road motor home where every bit of space is potentially useful and where the heaviest fixed items are ideally placed as low to the ground as possible.
The standard battery compartment will be moved to a more suitable location.
The (very heavy) towbar was removed.
The Exhaust stack was removed so that the exhaust could be re-routed to exit in front of the rear wheel and to gain a bit of extra length for the motor home body.
The tray was removed and the chassis stretched to be a little longer than the standard MWB (Medium Wheel Base) Canter,
Before and after the chassis stretch. 



The MWB+ Canter  :-)
Air bag suspension and oversize shock absorbers were fitted front and rear ..   The picture was taken before the motorhome body was moved onto the chassis and before the air bag suspension was attached at the top.
Timber attached to the chassis rails in preparation for the motor home base to be built and attached.