I'd love a Sugino OX601D for exactly that kind of thing, but £££. I think the sub-compact crankset idea is really useful but there's so little available. I think the choice is Sugino, Praxis (down to 30T with their special rings), Middleburn and a particular modular FSA crankset.
I have another bike (with a triple) for 'very loaded'.
I was thinking more 'bar-bag/saddlebag' kind of loaded