I've recently sailed Tornado single handed with spinny. It is a real challenge. I've only launched the spinny in light conditions while single. Seems to me, the main can be left cleated and near the centerline position, as heeling force will come from the spinny. Just keep the main and/or traveller line close/easy to reach as a last resort if you want to release it in a hurry. Plus, the spinny needs constant adjustment as puffs hit and apparent wind angle changes. Remember to head down in the gusts to control it. Easing the sheet as you head down only helps keep the power up, which is the opposite of what you want.

Enjoy!
Mike.