I don’t see why you couldn’t use the recycling boxes Richard, except that you will need to water your containers more than you would an actual garden bed, they would dry out easily I presume, that’s if we have any more hot weather – we haven’t seen the sky here for 3 days again because of low cloud.
Things like potatoes can be grown in compost bags standing on end and you add more compost as the foliage grows I believe, though I haven’t tried it myself.
Good luck with your trials.