the temp should not be a problem this time of year. While not a cold climate lizard, they are very resistant to cooler temps. I have an Argentine Black and White, and he seems to prefer cooler temps (70's daytime ambient air) with a basking spot. So as far as temp they should be fine. As for find a buried Tegu, thats more of a challenge. Maybe look for loose soil patches and "probe" them with a thin stick? Or just get real dirty and sift through it all. My outside cages are solid bottom.