Try to pack heavy things in the base and close to your back, not in outer/upper compartments, and make use of the compression straps to keep an as low as possible profile, and wear it close to your body i.e. straps closed tightly so it does the same movement as you do and won't swing.
Other than that, it's just getting used to it the more often you wear one.
Bought an avy airbag backpack at the beginning of the season, pretty heavy compared to the one I had before. The first two days I was also bit off balance but since I rode with it every day of the season, it became second skin.
BTW: What's you weght? Can't help with the SL or BG sizing since I don’t know them. Wrathfuldeity has a BG an IIRC rides similar conditions; you'll find posts of him filled with good words for the board.
"Yeah... no, that's not clumsiness, that's just being topographically challenged" ~ Noreaster
Last edited by neni; 04-29-2014 at 05:57 PM.