i'd aim a little higher with the temp on the basking spot, maybe another smaller branch so she can get a little closer to the heat if she wants to, or even use the light as a different temp zone and put something a little higher there, it doesnt matter (in my opinion) what the temp of the rest of the enclosure is, she will find where she's comfortable, and having a vertical tank means that if you keep the bottom at whatever the room temp is then she should be fine in the odd heatwaves. blocking upper vents in winter is a great idea, just leave a tiny bit open for air flow.
what wattage globes are you using ?