I wouldn't waste the coin on a 3 inch track, go ride with them and see how your sled hangs and go from there. If its that big of a difference (I doubt it will be) and it really bums you out upgrade next year. Also I think your right about not getting a turbo for AK. From my understanding of turbos and elevation you'd have to run a real high octane gas to run it at lower elevations and would still have to run it at low lbs of boost. It wouldn't be worth the turbo kit and gas money. But I could be totally wrong about this, I just know theres not a lot of guys running turbo 2strokes in AK, and especially since your riding up there where you rarely exceed 7k in elevation your not losing that much power from a naturally aspirated motor vs the guys riding out west where we are starting our ride at 6-7k and spending most of our time at 9k-11k
At least you can admit that you aren't comfortable tuning a turbo sled, especially if your out of Valdez. It might be a little hard to get things dialed in without some guys with experience with similar set-ups running around (seems like half the sleds in the mountains out west here are on boost now days) and without a dealer for the turbo kit nearby you very well may end up spending more time and money on tuning, waiting for parts/emails/info and burning down pistons than riding. Winter is short enough already to be out a week or 2 here and there for sled problems.
If anything get a fuel controller, get your clutching dialed in and maybe change your gearing if you haven't already. You should be able to make an M1000 an honest 190-198hp machine at sea level while keeping it naturally aspirated.
Keep us posted though on how yours and your buddies sleds compare.