I don't have that kind of soil where I am (higher elevation wine country foothills, summer dry and hot, winter cool and moist). Our soil is deep sort of silty, medium low fertility, fairly well draining, not the kind of hard clay in peru's waru-waru.
I dug a six foot hole with post hole diggers and had no problems going deep. Could have kept on going. (Soil was wet). Hardest part was first foot or so, probably from compaction (it was near a driveway).
Oak woodland / oak savannah. We're in the hills - fairly typical terrain. Seasonal stream, etc.
What are some ideal permaculture approaches specific to this region?
For my mind, the main importance is water storage and retention. Swales, lots of thick mulch, and (when there's money to dig one), a pond.
I guess what I'm looking for are the best general principles for this type of region. That includes ideal crops and ideal methods. Focus on trees? on woody perennials?
Also, peculiar tweaks or unconventional approaches for this region or similar regions.