Windvane! Autohelm (scanmar), Hydrovane, or Monitor (MRUD)
That way its already installed when you need it. Personally, I am very skeptical of the
spinnaker pole &
hatch board or droug methods. I would prefer something that steers almost as well as the original rudder. Sailing to Alaska? If you go anywhere near shore or inside passage be ready for currents up to 3 knots sometimes more in places you wouldn't expect. There are many many deadheads, jetters, whales and other things you can hit. A jetter is a submered waterlogged tree that, due to a change in water density/atmospheric conditions, decided to surface like a submarine. Get prepared for anything up here!