I've read that a typical white shirt is no more than 8spf, but I've never been burnt (or tanned) through any kind of shirt. I typically wear a light colored cotton t-shirt with a light colored cotton long sleeved shirt over...or a long sleeved light colored cotton T. Dark clothes are bad news. A towel to wet and wrap around your neck is great...a kitchen towel is about the right size, hand towel ok, bath towel too big. A safety pin might be useful. A hat that you can dip in the water (or ice chest) is also very good. A lot of excess body heat goes out through the head, so wear an appropriate hat. Floppy brimmed straw is my favorite.
Provide for AT LEAST one gallon of Gator Aid per person for each day. Water and potassium carbonate tablets are also good. Most "salt tablets" have potassium in them, but may also have sodium salt, which may cause problems. It didn't use to bother me, but now, I can feel it. My feet swell up more than normal. Avoid caffine drinks, and after hitting the beach, avoid alcohol. Both are diuretics, remove water from your system. You don't need that, for the weekend.
The Jills may resist drinking enough fluids, due to the toilet issue. I understand Roosevelt has floating Sani-Cans now, so be willing to stop and let them use them. We had one of the wives dragged off to the hospital due to heat fatigue at the J&J in Y2K...they are not used to the heat, the long hours in the boat, or the effects of heat induced illness. It's serious, and it's pretty scary. Gator Aid (etc) is the best solution!
Chapstick with SPF rating is worthwhile. Hand cream for evenings and after T. My hands are dry, cracked, and bleeding after a week over there.
Sunscreen: "Bullfrog" sunscreen is awesome, and waterproof. Major improvement over the usual stuff, which is barely worth applying. Apply sunscreen before launching. Rub it in well, and blot off the excess. It doesn't work instantly.
EYE DROPS: I have had some problems with (apparently) sweat running down into my eyes, even in the air conditioned truck, driving home. Some good eye drops might just help this, but I haven't tried it...yet.
Sunburn & Hypothermia: After getting too much sun, it's very easy to get hypothermia on a cool evening or morning. Why? Your blood has rushed to the skin, to aid the healing process. Solution is to avoid being burned, but also have something warm to put on, if you need it. Aloe Vera Gel is great for sunburn. At least one brand has benzocaine in it for pain relief. Usually one application will stop the discomfort.
C&R, Steve