Oops, I have to put a spade into this one.
My own van has the water bottle located inside the gas locker and guess what... it has a 12 volt pump attached with a junction box. All approved by the EU. The gas locker has of course openings in the bottom so any gas leak will sink and the junction box is located at a top corner.
As this type of situation appears on many EU vans I am not so sure the concerns are really as dramatic as described.
Yes, if you have a gas leak and an electrical spark, then yes, there is a possibilty of a problem, but we are talking 12 volts here and inside a plastic box, so the chance of this occurring is so small as to be not worth worrying about. 230 volts however, and yes, I agree that is not on.
I would be more concerned if the coolbox as described is located in the locker itself, then there could be an issue as the motors are usually exposed for cooling. However, if the cable is going outside to the coolbox then I do not see a problem. Just do not tie the connection to the gas cylinder and make sure if there is a junction inside the locker that it is inside a sealed junction box.