I use a gallon container and pour into that (with a clean funnel). It can be a little tricky but doable.
I'm an oil consumer that would benefit from the old 16 gallon small barrel size. I would love to get Euro 0w-30 and HDEO 5w-40 in that size. It would last me a couple of years and be worth the investment of a hand pumps and secondary containment. 5 gallon is too small (might as well buy in gallons, which I do) and 55 gallons is way too much.