Wow, thanks very much for the good advice, Thorburn! Is it possible to edit my old post — I’m logged in but don’t seem to be able to at the moment.
In the meantime, here’s another go at the photos using Pictr
My undug plot starting to the right of the stakes:
Yes I will carry off the stones!
Closeup of a crackly bit:
Closeup of a more average bit:
Advice on feasibility of just plopping a raised bed on top without disturbing the lovely hard pan is greatly appreciated.