I weigh 175 like the OP and mostly ride a 157 Proto in Nagano. I used to ride a 158 2011 Highlife among many others.
On Deep days I ride a more pow specific deck, but you seem to be looking for an all mountain, freestyle friendly pow capable deck quiver of 1.
Since the Hokkaido pow is deeper and the runs are flatter than where I ride I would say go with something in the 160 area plus or minus 1cm.
It could be twin or slightly directional IMO.
There are so many good boards to choose from and since you already have many recommendations I won't add to your decision making trauma.
I will say that in general I find C2BTX style profiles to float better than R-C-R at the same length. I also don't like stiff decks (T.Rice is stiff) for the Japanese powder and tree runs which are often tight so some flex really helps.
To sum up, for your needs my vote goes for something in the 160cm range (plus or minus 1) with a C2BTX profile and midish flex. Either a twin or a slightly setback directional twin.