I always think about doing it when it's below zero outside as I figure then it should work with bags and ice blocks.
Then I am lazy and do nothing until next winter.
Good modern coolboxes keep stuff frozen for comfortably 24hrs, pushing 48 if full enough. Should be plenty if you clear the big chunks out. Keeping it outside is a great shout.
Don't have one of those, and before I'd buy any big boxes there is tons of crap that needs to go that's not food related...
But our low frost thingy looks ok right now, approach last time was to just buy a new fridge/freezer.
I always think about doing it when it's below zero outside as I figure then it should work with bags and ice blocks.
Then I am lazy and do nothing until next winter.