I made it down to Ft. DeSoto this weekend, and here is what I found. First, you can put in a cat behind the main ranger station (which puts you into the main shipping channel, but with plenty of room to sail since it's miles accross) but you do need either 4-wheel drive or beach wheels since the last 50 ft. or so to the water is very soft sand. And yes, you could also launch off of the very wide concrete boat ramp, but that puts you into a small bay where you have to then sail out a VERY narrow channel to get into the gulf. LOTS of motorboaters in that area on weekends, so be ready to navigate quickly if you go that route. But the best I saw was just preceding the final small bridge as you approach the entrance of the park proper (before the campgrounds). If you go to the small beach on the right, you're in the same small bay as the boat ramp, but if you go to the small beach on the left, you can sail directly out and toward the Sunshine Skyway bridge. Likewise, there are numerous fairly wide openings between mangrove trees on the causeway approaching the park where a person could easily put a cat in, again on the left-hand side if you want to be in the main water of of the Skyway right off the bat. So it seems to me (since I don't have 4-wheel drive or beach wheels) that the best place to launch from is actually before entering the main park.

Regarding the raccoons, they are still numerous and exceedingly brave. Don't camp there w/out tying your tent together--otherwise, they WILL undo the zippers and join you. I was told that last summer they removed 500 of the rascals from the park, but the population is unphased.