Given some unexpected free time, I did a little 3D cad of what I want my solar panel system to look like. Crude and lacking in details, but in overview, it will look like this:
Today, I found the manufacturer's datasheet for the battery. DrJim, Quizikle and the other engineers who drop by here will probably understand how I almost let out an audible squee when I found it. According to the datasheet, a constant current discharge at 10.4A (naturally not on the datasheet) can be interpolated to be around 2 1/2 - 3 hours (probably not as much as 3). It didn't make it, but I haven't been very nice to this battery and have almost thrown it out before. Often, old lead-acid batteries can be revived by charge cycles. We'll see.
Finally, from the "don't ask me how I know" file, if you need to gather water and you don't have a plastic barrel don't forget canvas. Canvas can make a pretty effective water barrier to line something with. It will hold water indefinitely.