Loss of core temp is cumulative. I took a 5 mil to Bonaire and was glad I did. As many dives as we were doing, I'd not have been able to in a 3 mil.
But that's me. No one can say what's right for you except yourself. No one.
If it was me, I'd take a drysuit with two sets of light undergarments. Not just for changing due to ripening of them, but because at the end of the week after 3-4 days of 4 dives a day. And I would think you could alternate between sets to reduce the funk and maybe rinse a set out and let it hang to dry in the sun while using the other set.
Having the option to double up would ensure I enjoyed my dives without the risk of hypothermia. Yes, you can get hypothermic in 80-degree water. Start with a low enough core temp, not enough sleep to generate internal heat, etc.
My Gf took her drysuit to Turks and Caicos in August. First day on the boat some people gave her funny looks. By the end of the week they didn't as they sat between dives shivering with blue lips and she was there just relaxing, warm, and dry.