Well, here it is - finished.
I must confess that I am happy with the results and would definitely consider incorporating that into many sketches going forward.
As simple as this little mat was, getting all the elements to separate in values was a bit of a challenge and I hooked the water a few times to get to something that didn't blend into the trees.
This picture doesn't really show the separation.
But, I do like the underpainting part. So, I think tis exploration gave me the results I wanted.