Your arrangement makes sense. I think one diode per panel will be useful if you have any shading issues at all, but cost you a few % output if you don't. Of course, it wouldn't help with a panel going open circuit, but it sounds like you have that under control. One thing not mentioned....a fuse near the battery, or ideally in its box. I have a little 'micro' system I set up, 20W panel and 40 Ah battery. I put a 30A automotive fuse in the box for safety. While it is low voltage, a big battery can certainly start a fire through a short.