I've expanded the body to 1900mm wide (same as a Jeep Wrangler) and 2750mm long. This has given me two 300mm deep storage areas at the head of the bed, and one side of the bed. Plus theres still room for storage above the foot of the bed.
The problem with my layout was that the kitchen and fridge both had to fit between the wheel arches, so there was a heap of wasted space behind the wheels and the width of the kitchen was limited. To get around this instead of having a slide out kitchen I can have a drop down kitchen, which means the kitchen can be much further to the side. This has other advantages that I don't need to figure out how to assemble it inside the camper under the bed, I can use a hinge instead of a drawer slide, I can legally keep the gas bottle in the kitchen, I've gained more storage underneath the bed, and I can fit a drop down table on the opposite side.
The table as it sits is only 300mm wide, and there is only just enough space to sit between the kitchen and the table, but I will try to make it wider and in nice weather you'd sit on the other side anyway. The box with the kitchen will hold pots, pans and cooking utensils. The table box will make a good pantry.
I've also added a ~170L tank between the wheel wells, and there is room for electrical and plumbing behind the wheel wells under the bed. Not super easy to access, I'd have to lift the bed base up, but it's a nice spot for it anyway.