Well I ended up making one small change to the cold frame. Last year I used 6mm plastic for the top and it worked fine. I couldn't find a wide enough sheet of that for the top this year so I tried 4mm. It didn't work. It was too stretchy. The result was that no matter how taunt I pulled it, when it rained, puddles developed. If it rained alot, giganormous lakes developed that sunk to the bottom of the frame and would have squished any baby plants below them.
My change to the frame used $4.24 panels of plastic. The kind you put in ceiling lights. I attached them together with a duct tape hinge for easy opening and closing and its working a lot better. Nights are still running in the thirties here, but my interior frame temps never go below 48 degrees.
Currently in the frame I have chard, lettuce, spinach, a few herbs, leeks and six cells of unsprouted amarynth. I hope that doesn't need heat. I have no room for it inside. I also have one Fat and Sassy pepper in there which is much smaller than the peppers inside, showing that peppers like warmer temps, lol.
I thinned the lettuce out today and had a little micro green salad with the thinnings. The first harvest of the year! I also transplanted four tomato seedlings into bigger containers and put them in the cold frame. They each have one or two lower leaves that are looking a bit off. I think it may be because I got some neptune's harvest on the leaves but I want to separate them from the other plants just in case it is disease. I'll re-revaluate them in a couple of days.