We bought two galvanised bins years ago, one with no internal divisions, the other with one. They have been well worth the outlay. Previously we had, in our innocence stacked feed sacks on a pallet

. Then we tried a plastic dustbin but rats gnawed through the lid, fell in, couldn't get out, ate all the stuff in there, then ate eachother

, leaving just one which I assume died of thirst.
I think galvanised dustbins would work well, with the advantage that you could lift and tip them to get the last dregs out. Can't you get a design where the lid twists on? Or you could use a luggage elastic from the handles on the side, up and through the handle on the lid to the other side handle. Rats might gnaw through that eventually, but I think you'd have time to notice.