Thanks Bob, Oshyan and Aaron...

The final few tweaks, before I hit the render button:
enabled receive shadows from ... in the steam... looking good so far(?), & did not impact too much on render time, Jochen's amazing LR 110's (big thanks Jochen!) added a paint job of my own...

You can see in the larger FG crop that the tyre tracks are obliterated by the shadow of the rocks that were out of frame... I always forget about wee thing like that... testing soft shadows at present, will post more soon,

anyone used a render farm for single images yet?
severely tempted lol!

)
J