Over 90 seems quite warm. Our sulcata also searches for cooler areas when his box gets that warm in summer heat. Shade over his box was installed for this summer. I heat his box from 80 to 85 in winter. Temperature stays pretty constant with a well insulated type of entry. The entry is made with 3 layers of flaps made from outdoor carpet.
Also waiting to see what others have to say in response to your questions about heat.
Also waiting to see what others have to say in response to your questions about heat.