It could work nicely. If you've been there long enough to see the annual solar pattern, you can judge. Box turtles will generally do fine. They don't really bask that much anyway but generally like to sit under filtered sunlight which is usually why its best to have a lot of sun exposure so they can choose when they get their UV.
Given how warm it gets where you are, it won't be a problem at all. Just preferable to have as much sun as possible on the property.
Its sad. I bought a house recently and I pretty much chose the lot based on space for the turtles and sun exposure. Call me hooked 