An alternative to a moleplough or a digger is a trenching machine. If the ground is relatively free of rocks, then a sort of ground-chewing chainsaw can be used. B4RN Norfolk have one on the back of a tractor. Norfolk claims to dig to 90 cm with it. It is a tractor attachment the same way a plough is.

Northerners may decide this is unsuitable for their terrain.

It is the same concept as the hand operated Toro or Bareto machine.

B4RN have a Toro machine, but that doesn't mean you can get hold of it. It needs a short training session, then if they trust you, it might be possible. You would be paying for a few new chains before you returned it.

Looks useful for that really fiddly bit, if you had a machine freely available. Looks as though you need an operator as well, it's a bit unwieldy. And one immediately is thinking about what size stones it can deal with and how easily they damage the sawing chain.

And there exists something like a hand held version which has got to be the most dangerous machine ever invented. Do not use.