Pretty much agree with everything TT has said but on this issue, I would caution you against making stance changes. Stance is a very individualistic thing and plays a very important role in riding performance. Changes to accustomed stance take awhile for the body to adjust to; generally longer than you have available.
Duck stances really do not inhibit off piste powder riding performance in any significant way. I ride 15/-15 for everything including on my splitboard and my stance works great for me and I ride 90% off piste terrain even while confined to resort riding. Any slight performance advantage from a forward stance will be significantly countered by your body's unfamiliarity with a new stance. Dealing with challenging (though fun) conditions will exacerbate this even more.
I do however fully agree with TT's advice about a pow specific setup if you have those conditions. His advice on that is solid.
Right now I ride -3, +15 (goofy) so stancewise I'm already a bit forwardish. Will def rent a powder board to practice.