GeoOrbit has all sorts of helpful info.
Look at their link under: Other Good Information
Also, other members have linked to additional sites whenever this question has been asked in the past.
So, there are multiple resources to review. -
One consideration is to have the dish high enough to be able to easily mow or walk under it, as you see fit.
But, if it's too high, you'll need a really tall ladder to work on the LNB, especially if the dish is at True South.
The more south you are, the higher the dish will point.
The LNB is lower when the dish is all the way east or west, but that's not necessarily the best place to work on it.
My 8½ foot Birdview was 7 feet above ground, on a 10 foot length of six-inch diameter mast.
The AMCI 8 foot was free standing on the same pipe you called out, and 9' high.
It was sturdy enough, but I certainly would not have gone higher with that hardware.
I cut off that pipe at ground level, intending to bury 3' and have 6' above ground.
If your dish is 10', take that into consideration.