Honestly you're asking for something that is a lot tougher to design than you'd think--small enough to carry in a 2 door at all times, easy to install, easy to uninstall, sufficiently water tight to survive those Florida monsoons that come out of nowhere even while driving, and sufficiently sturdy that it stays firmly and reliably sealed on the Jeep even at highway speeds. I have not yet seen something like this.
So, your main options that I'm aware of . . . .
what a Bikini looks like. Geoff would know better about how easy this is to put up, take down, and store within the Jeep itself (especially a 2 door). I'm not very hopeful.
. If you're willing to pull over and wait out any storms, you could go with a Bestop Trail Cover like this
. That fits the bill in terms of size, speed of assembly, water tightness, etc., but you would obviously not be able to drive with it. I also think it would be pretty weird to be sitting inside it in the dark waiting for the rain to stop.
. In the "it's better than nothing" department, you may want to consider designing/creating something yourself based off of or similar to a SpiderWebShade like these
. They go on easy with no real hardware (save the rubberband type straps), stay on at high speeds, can be packed up small in a bag, and would give you some sun protection too during the midday blaze of Florida. The downside is though that it is a mesh, so rain comes though it. I'd suspect you could work something out by combining it with a tarp-like material from Home Depot or some such thing. Better than nothing I suppose.