Now that the Calor gas lites are slowly disappearing, I want to always have a spare bottle, so do I have to go and buy a small propane is it a 4.5 kg or do i carry a full Heavy bottle cutting down on my in van payload which I find is already up to its limits with the lesuire battery 25KG, The motor mover. 35 kg. On my caravan a 2013 560 VIP there is no leeway on a data plate. We already have the lightest things possible in the van. I wonder how overweight other folk must be. Must need a bigger car with more payload.