Hey @Roscoe P Coltrane how did you get on with this? I'm in a similar situation, I've been using my van as a camper for years but its reg is commercial so I'm taking the next step to change registration but I don't like this idea of having an internal kitchen but I have to make one to suit the conversion criteria.
What I did in the end was put a gas locker on the side of the van cut through the side panel. This gas locker is a form of dense polystyrene and is primarily intended for boats. Its main advantage is that the door opens to the outside and has vents to the outside so the locker itself doesn't need a gas dropout. The cooker is mounted literally just above the locker so the copper gas pipe is literally just 1 ft long. Its very advisable (if not specified in the regs) that the cooker has a thermal shutoff valve incase the flame blows out.
https://floatyourboat.co.uk/product/gas-bottle-storage-locker/
You will need a gas dropout wherever there is a joint or tee in the copper pipe and these dropouts are quite large (I think at least 70mm across), this means that you need a gas dropout under the cooker itself. A carefully designed setup can get by with just one gas dropout - but if you go for an internal locker you will need at least two - one below the locker and one below the cooker.
The gas fitter will check that you have met the specifications that he has supplied but he will also perform a sustained pressure check for leaks.
My first quick and dirty install used a meths stove (which I borrowed for the SQP check) which bypasses all the gas regs - not really a sustainable solution though.