The genoa or jib is not much of a problem...no mast to clang against.
I would just keep it tight, so that the halyard doesn't wrap around the forestay. So a bungy cord or a sail tie from the shackle to the bow pulpit. But then you'd have to go forward to undo the bungy? So why not just undo the shackle.. The jib could set itself if left unsecured.
The mainsail clanging could be reduced by leaving it attached to the shackle and then tying the halyard off to the shrouds with a sailtie....but then you still have to undo that! And your not going to get the top of the halyard far enough away from the mast to reduce the clanging completely.
So my guess is that your quietest solution would be to undo the main halyard..and sail off with the headsail if you want a compromise.