What boat are you on?
I’m on flight over now and will be diving Hurghada a few days before and then am also doing 2 weeks back to back, ZRD and BDE, starting on the 20th.
I’m a bit committed now as my wetsuit is in my luggage below. Looking at Port Ghalib, they are at 29C/84F. I have dived with a 5mm in many warmwater locations (Indo, Philippines) and the expected temps are within the window of other places I’d be wearing it at, especially if thermoclines are 27. Though, it’s probably more of a 4mm by now. I tend to run colder than most people and have yet to feel hot in a wetsuit on a dive. With so many consecutive days diving, I’d err on the side of warmer. Some other folks might just be in a skin!