What are you allowed in you cab in regards to gas for cooking?
I must admit I had a 4.5 kg propane bottle,and I know of others (not many) who did also. 
I found I could run a double burner stove which obviously the small gas cannisters cant do and also the cannisters run out quicker and are more expensive than calor gas.
I just would like to know what is permitted in your cab for future reference 
as a few people laughed when they saw me cooking large scale dinner parties on my camp stove
I must admit I had no idea when I started driving that a bottle would be a problem,but I did worry what would happen if I was in a collision.
I think the only dangerous gas canisters are the one like camping gaz which pierce the top when you screw the cooker to it, these can leak and cause an explosion or at least take the eyebrows off 
I know.
In Germany and many parts of Europe night heaters are powered by butane / propane with two 11kg cylinders fastened to the cab wall or the chassis. These are the best night heaters you will get as the fuel doent freeze like derv and leave you without heat.
I had a Electrolux Fridge which ran off Gas and as long as the connections are made using proper fittings and not a taped up pipe they are fine.
I saw the mess that gas cylinder made to the DAF in Zeebrugge when it exploded in the cab, that was the fault of the driver turning the gas on and not lighting it straight away, the inquest decided he woke up and lit a cigarette.
I would use one and if the TUV and BAG allow them, to me they are safe