Congrats on going to hakkoda, its a dream of mine.
What you are doing is all side country and close to roads and lifts, you really only need a small pack for extra layers, and water etc. You want vertical board carry but those boards on your back get real heavy after a few runs trust me and the board has a habbit of banging into your leg with every step.
There is an art to packing your snowshoes and poles into the bag when you are riding too so make sure you work out how you are going to do it before you hit the mountain. Also 3 piece poles are the go