The Bongo has the Southernimports Mid conversion in which has a 2 burner hob mounted in a kitchen like this...

Now we're quite limited on space, the cupboards under the kitchen will house the coolbox like the one in the picture, and the fresh water container fits in there too. We won't be storing the portapotti there as I don't like the idea of it being with the fresh water supply bits! It will go behind the rear seats if anywhere.
Basically I'd like to take as little space up as possible. I don't imagine us using a lot of gas as it is only the 2 burners in the van that use it. Saying that we do have a mini BBQ that runs on gas, and we do have a little 2 burner/grill camping stove that we may use for longer stays to avoid get the smell of bacon over everything.
I have 2 butane bottles which are both empty at the moment. They are the smallest standard size (something like 4kg). Am I best sticking with these? They are a bit of a pain to swap between the bbq, camping stove and built in hob as they use a screw thread regulator. They are also quite large.
Would I be better using the camping gaz type bottles instead?
Any suggestions?