Thanks Roger,
I plan to cast long threaded rods into the concrete (pre-bent) as you suggested. I live in an area with very solid clay soil (there used to be brickworks all over the place in the 1900s and large clay pits in the ground, they have since been filled and council has created many parks on top of them).
Matt, thanks for the advice re taking off the thin plate and re-weld a 10mm plate. Just checking I will need 400mm long gussets, a slight overkill given the load capacity of an EQ6?
Bo