There is a large advantage to riding clipless. That's the reason every single serious road cyclist uses them. On a 200k brevet I was once stuck at the back of a long line of slow riders who varied in speed a lot. I finally decided I was plenty rested and went up front to see what was going on. It was a young man riding fixed with flats. We had a long 8% hill coming up. I asked him how he'd handle that. He said he'd walk. If I'd been riding fixed with clipless, I would have ridden it just fine and I was more than twice his age.
But to answer the OP: hold onto the bars. That's the key. Take the impact on the whole side of your body, so it's distributed. That's what they teach to the bike cops and I can tell you that it works. After you're down and your spinning along down the road, pressing your helmet into the road, hard, will cut down on the upper body road rash. You'll need a new helmet anyway. The biggest bummer is ruining a lot of expensive cycling gear. Riders heal, Campy doesn't. Tegaderm applied over Povidone liquid is the best for road rash. If you do it right, it'll heal with no scarring. Have to scrub it with a brush until clean first. That's worse than the crash.
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