If the water is very flat and the wind light (3knts), I find that I can ease the halyard and the tack line while crew sits on the windward side. The spinnaker will rotate to windward and you can work the boat further downwind. You have to be patient in working the boat down. Unfortunately, the spinnaker is pretty unstable at this angle and any wake or shift in the wind can cause it to collapse badly. If that happens, you'll have to heat it up and start over again. Rapidly heating up doesn't always work, because there is so much slop in the halyard and tack that it may just flop over to leeward. You'll have to play around with how much you can get away with easing the halyard and tack. Also, having a new spinnaker seems to help. An old, soft spinnaker doesn't 'stand up' very well on its own and seems to collapse easier. A newer, crispy spinnaker seems to be easier to keep full.