I've completed the first two Cold Weather boards.
After the previous steps, the grey speckles just weren't dark enough for me, so I brushed areas with devlin mud, hoping to give it a kind of bare earth colour. It came up a lot darker and solider looking than I had hoped, so I drybrushed codex grey over those areas, as my craters and figure bases are codex/mud/dry brush codex.
The idea was to help blend the darker terrain objects into the board by adding dark patches to the board. I tried putting terrain on it when it was all white, and the brightness of the white made it so everything on it looked too dark and without detail. With the splotches of mud/grey and grass, the scenery doesn't look so stark on the board now.
Anyway, I also glued down patches of grass as well. Overall, it looks a bit rough when empty, but I think it's all right once terrain is put on it.
Once I get more glue and more of the white rocky stuff, I'll make two more boards, and then I'll have a whole table. Sorry the photos were so dark, I didn't take them in my usual spot. Better photos will likely come.