Thanks for all the information, and pictures.
I have been studying your wicking beds and have a question. It appears that the overflow pipe is set at the elevation of the top of the scoria. It would seem to me that this would not allow for much wicking, doesn't there need to be a connection between the water reservoir in the socria and the soil for this to work? Water does not wick very well in course material.
My raised beds are already built, but I am thinking about some modification that might make them work more like yours. I used ~1,000 liter fiberglass tubs, cattle watering tanks. I put a layer of about 6 inches of gravel in the bottom, covered it with geotextile and then put the soil in. There is a drain at the gravel layer to prevent water logging. I could put a riser on the drain to allow the gravel to become a reservoir to have a similar effect. But need to figure out the right elevations.
You are right, your climate looks similar to Florida, south Florida more so than the north where I lived. In the north we had no dry season.
Beware the attach worms!