richard,why don't you buy your own cylinder and fill it up when needed at a petrol station?
because
1- don't think they do a small 6kg one.
2 - the set up cost is high.
3 - cutting filling port into side of van
4 - have to go to garages to fill up
5 - wont get gas at trade prices
those are the main reasons
at the moment I get all the gas at trade prices and I can walk in, pick a new one up and walk out with it with-out paying and pay another time! lol