Your basking lights may be towards one end of the dirt area in the cage, but they are still near the center overall. You have a 4' fixture in there which is not quite to the end of the cage, and the basking lights are just inside the end of that fixture that is near the center of the cage. You stated the cage length as 7.5', so that would put those basking fixtures pretty close to center. I'm only bringing this up as it will be harder to get a proper temperature gradient from one end to the other with that setup. If I'm still not seeing something right here, could you please take a shot of the whole cage from straight on, and from low enough the fixtures can be seen, and post it? Not trying to give you a hard time, it's just that something isn't adding up for me here.