Hello Chris,
I've had this in mind too, though I haven't done it. I don't know if it's standard but my deck organisers have an eyebolt on the top, to which I could attach a block. If yours don't have that, you could probably fit one in place of one of the retaining bolts - but that would mean finding out about the nuts...
Otherwise, I'd have thought fitting a second set of organisers on top would be the way to go. I don't know about the nuts but I hope they're bonded in place like the ones that are visible under the side decks. You'd only find out by undoing one though, unless someone else can tell us...
Anthony Russell
235/02 Sea Wyche
Anthony Russell
235/02 Sea Wyche