From what I here from successful keepers they need humidity around 50%+. They will get dehydrated and die of kidney failure if you do not, even with a water bowl. ALso the basking spot of 120F+ is an absolute must for proper digestion. Best substrate is 50soil 50% sand. If your savvana can burrow in what you have now it will be fine. He looks healthy and fat. Just keep his diet up and watch him grow. Are you planning a DIY cage? If so we would all apprciate a thread on that. Again nice looking sav and good luck. Post some more pics when he gets big.