I have 2 3-liter frozen Zephyrhills bottles of water that fit nicely in the bottom of that cooler. I also put maybe 6-8 20-oz frozen bottles of Gatorade. Anything else that I can freeze goes in there. Finally, if doing a "long" trip like this one, I will dump ice cubes in. If kept out of the sun, that will easily keep our fish until we get back to Chok. The cooler and contents are usually close to 50#. I weigh 200# and have lots of gear, so I'm sure you will be fine. The 2 Zephyrhills bottles are not for drinking, except in an emergency--which I have not experienced, yet. They are for cooling.
Yes, lets plan on fishing around Lostman's. We can camp at either Hog or 6 mi further south at Highland. Actually, I've just looked at the tides in the area and they are quite unsymettrical--fair tides at night, but rather low tides in the morning when we will launch. Highland is awful on low tides and would likely limit our fishing. Hog will be a better place, and you can fish around Hog as well as Lostmans.
Regarding parking at Chok. I've never thought much about it, but there was an incident between a powerboat fishing guide and kayakers which resulted in some tires being slashed last spring. On the other hand, a friend and I are doing a trip out of Chok starting tomorrow for 4 days (3 nights). We plan to park on the causeway. I think it will be fine, but, if not, I will let you know.
As Quirkster says, any of you want to join us on this fishing trip (or to sight see), you are welcome.
I sail: S FL, Key Largo, Everglades to Cape Romano, Ft Desoto, Cedar Key
"Any intelligent fool can make things bigger and more complex ... It takes a touch of genius and a lot of courage to move in the opposite direction." A. Einstein