I've just moved the boat to save dragging a trailer across the country with the associated:
-reduced speed limits
-increased maintenance on trailer
-storage issues at home
-fun of reversing on single track roads to passing places
-increased fuel consumption
So whilst a trailer is probably the right answer it is not a solution I am going to adopt (not to mention the purchase cost).
I'm leaning towards Jambo's solution (although the general thinking seems to be steel jerry's have less odour?), filled outside the car, wiped down and left to dry whilst paying - and then loaded into something like this http://solentplastics.co.uk/008432%2...20Box%20XL.JPG
with a newspaper in the bottom (and maybe an air freshener too!).
the trick will be finding a box which is a good fit so the cans don't rattle around and it doesn't consume any more boot space than is essential.