I want to end up with something like this below

Has anyone done this already - I couldn't find any previous posts - and if so do you have any tips/photos to share?
I'm imagining 2/3 separate units with lockable castors on each.
Units would be secured to the van with pressure catches to the floor/body when in transit.
Pull-up worktop extension to bridge between the units when outside.
I fine to make the units, what I'm not sure about is powering the cooker ignition and water pump.
I suppose I could extend the 12v power to the units and make a simple connector, but I'd prefer a neater solution. Would a small battery pack to the job? I ain't no spark.
Any advice welcome.