JA I like your thinking. I noticed that Jaycar have weatherproof outlets which I could fit simply into a cover. If they get dirty, a quick blow out with the air hose would fix it. Yes, I'd run the cables through conduit.
Glen I was preferring to not put a post in because I have some constraints: occasional foot/dog/motorbike/mower traffic around the yard, I wasn't planning on installing a pier on the slab, and the slab will be smack in the centre of a walk through area.
However, If I go ahead with the in-ground approach I'll configure things so I can revert to a post if it doesn't work out. Ahhh the tinkering
