Luckily I had help, in the form of Paul the gardener.
We marched the formwork across the field. For other, heavier, things, we used the lawn tractor with the trailer.
In order to use less concrete, we put a base layer of flint (there was lots lying around, of course). It worked well to space the wire mesh, too.
We stretched a chain of extension cords across the field in order to get the concrete mixer going. We also had very long hose, but it didn't stretch quite as far as the slab. We left the hose running for the entire afternoon, which I felt very guilty about.
Moonrise over the field after the rain.
Just as we finished, there was a downpour.
The surface is very rough, but eventually it will be tiled over.