Keep in mind that a big pool doesn't keep it cool, especially if it's only 5' deep. The deeper the pool, the cooler it stays, not really the larger surface area. But it's probably not that much different anyway. Pools in TX get hot, more-so with dark plaster and sun. But your infinity edge will assist with cooling through evaporation, especially if it is an aeration type versus a smooth drop. But the aeration over a rock ledge with cause pH rise quicker.
Martin - If you're here, how does your pool temp do in the deep south?
Lights-wise, good to go with three. However, please create a signature to show your pool details, including size and dept profile, planned equipment, etc. That will hep aid the conversation.