Or consider metal fencing. I'm decking my new smallholding out with Clipex metal posts. Everything can be banged in by hand (incl strainers) pretty much (unless like me you've hit bedrock, oops).
Not cheap but is very quick to put up so you save on labour time. Will not rot, should last 30 years.
Finding a contractor that does it might be tricky, but I'm doing all mine myself pretty much it's not hard.