Best stain to hide walnut tree spots and blotches?

Sadly, my deck lies under the spread of my neighbor's huge (and prolific) Black Walnut tree. After one year of weathering the new PT deck from last summer (left untreated to cure) was covered with stains, spots, and blotches from fallen nuts and leaves, helped out by squirrels leaving their walnut shell lunch debris behind.  Even after a strong power washing much of the discoloration remains, as in these shots:

  The first two shots are areas which have also been random orbital sanded with 50 grit paper.  I want to use a dark stain to hide the unevenness as much as possible.  I like a dark effect (even dark walnut!) but am not sure what type, brand, and opacity would do the job best.  I do not want a completely solid stain.  Is further prep needed? Would AC penetrating semi-transparent or semi-solid work?  TWP wet-on-wet? (I was narrowly saved from Arborcoat by discovering this website--thanks!).

Randall