Hm, very clever idea, but a 'hoop house' with clear plastic over it - like a small makeshift greenhouse - might have worked better . . .. not to aid and abet you in playing around of course, but I love to mess with that kind of stuff, too. A lady on the other forum lives in Red Oak TX and keeps tropicals alive through the winters there with a hoop house. The key is to warm up the soil around the plants when the sun shines during the day, then 'trap' that heat around the plants during the night. Your frost cloth might have prevented the soil from warming up.
A fellow on the Florida forum takes cuttings from his tomato plants at the end of the season, and starts his new plants from those every year.
