well all I have is cabbage and collards now and I'm sure they will be ok tonight. We cut our first cabbage yesterday and had cole slaw for supper. Our goal is to keep the collards alive for the new years meal.

Here is a link that might be useful: Check out the Barry Gardens

I have all my veggies tucked into tents right now. They are usually fine. The radish have a layer of fiber cloth under and then the plastic over (floating, not tented, they need this a bit more). I've never lost anything under tents, and at church we have never bothered to cover carrots, beets, or broccoli. Your chinese broccoli may have problems. Mine is already beginning to fade. Mine is tented for the evening.
Laying old sheets over things also helps. When they are in the ground I use short stakes to hold them up between the veggies and just weigh down the sides and ends to keep the sheet from floating away in the wind. I put a stick in the middle of a container and then throw an old pillowcase over the whole thing...