Rapid set in rammed earth?

Building a new fence, I normally do stabilised earth and ram it hard until it rings.
I've got a half bag of Rapidset left over in the shed and as the stuff has such a short shelf life I want to use it up before it dies.
In a hole 300*300 and 600 deep would a half bag of Quick-set be enough to set solid?
The other two holes of the same size and depth I just used cement powder mixed in at the approximate ratio of a handfull per shovle load of dirt and thay seem to be as solid as a rock [almost anyway] and not likely to move for a decade or so.