I dive most all summer in the Bahamas and it can get into the high 80s. After a few hours you get cold.
I would suggest 3mm with removable hood. So you can rip it off at deco if you get hot. 1.5mm gloves if absolutely necessary.
I wear full Kevlar akona gloves and my hands never get cold. Even after 6-7 hours in the water.
Im a huge cold water wimp. I couldn't imagine wearing a 5mm