Thanks guys; I'll get there - it was one of those weekends where things were lining up for getting stuff moved around easily, so it was worth asking now.
@austastar We have more 25 litre buckets than we know what to do with as wife works in a bakery... The dog has 3 water buckets dotted around that are all those type of buckets, and we have a stack in the shed.
@KeithB I've managed the same, finding plenty of the big barrels; it's the 50ish litre ones that I'm struggling to find.
@Hoyks thanks for the offer - I might end up meeting you this time!
Sometimes it's a case of finding the big barrels and then looking for the smaller ones from there.
The 60 litre ones like these are plan B:
(
https://www.tilkey.com.au/new-drums/)
Bit big for the trailer, but great for the dog food in the shed.