Just a thought.
Do you HAVE to dig a hole? Acquaintance recently went to lot of trouble doing so. Then saw our set up!
We have loose bi-pod of two tree sticks (cost nil) tied together at top, clothesline is looped around that and then down to some sort of back stop; in our case the trunk of a tree to which it is looped through a piece of hose to avoid chafing.
Other end of line is secured to corner of small shed which is sufficiently substantial to take the weight of wet blankets etc. Line is about 25 feet long.
Advantages: Bi-pod can be used to loosen/tighten line; bi-pod can be laid flat on ground to allow wheel barrows or even our vehicle to be driven over/past without detaching anything.
If it is necessary to detach line, the other end can be slipped off the hook in the shed and the laid back against the tree that is used as a back anchor, about six feet behind it. Very flexible and economical.
The metal cored line doesn't last for ever though, once water gets through the plastic coating. Especially in this climate next to the North Atlantic! But another 50 feet or so costs only a Canadian few dollars.Also btw the metal line although only six feet or so above ground can also be used as a radio aerial. Capactive coupling without actually attaching to the metal core (and thereby letting in water!) can be achieved by wrapping turns of wire from the antenna post of the radio/wireless around the clothes line a number of times. Not been very successful picking up the now 198 kilohertz (used to be BBC Light Programme on 1500 metres) on this side of the Atlantic though! Cheers.