I have some slatted shelving although. I have used pallets, suspended chainlink fencing or weld mesh in the past.
In terms of drying I think ensuring that no moisture remains in the stems is sufficient as it is this moisture that will cause the problem during storage! Placing them upside down usually satisfies this need even in wet weather., add to that .....the rain will wash them clean!
Then when you think they are dry dress them ( remove flaking skins) this will remove any overly wet skins then put them in store. If you are unsure as to whether they are dry enough to store do not tie the necks and this will allow any surplus moisture to drain / evaporate off!
As always when in store eat the thick necked ones first as these are the ones most likely to rot!
Well that is on way and I would imagine a few more methods will follow!