I built some A-frame greenhouses over some of my raised beds this season and it bought me more than 5 weeks of post-frost ripening time. I built them out of 6' lengths of 1x3 furring strips and huge sheets of bubblewrap. Taped the ends closed at night and opened it for venting during the day.

Without them up here in the mountains, I'd have lost a lot of my crop of tomatoes, peppers and especially, eggplant.

Tomatoes are pretty frost tender. My squashes died first, but the tomatoes were only a few weeks behind. I protected mine through a few frosts with the big x-mas lights on the tomatoes, covered with sheets and then garbage bags-watch the lights will burn the fruit if they are righton them. They did survive very light frosts but once it was a reliably freezing they were gone.

Of the ones you mentioned, my nastys lasted through some frosts but were taken down by a good freeze about 25F I think, swiss chard and beets are pretty cold hardy, they are still going strong into the low 20s, radishes are somewhat cold hardy but I think it depends on the type, there are winter and summer radishes and I'm not sure the difference, basil will start to show black spots by light frosts but any freeze will kill it same as tomatoes. I'm not sure on lettuce, it is more hardy but I don't know how much and I think it depends on the type.