When all else fails for winter trout, use a wooly bugger. Get it deep and move it slow as mentioned before.
Your 5/6 weight rod will land a winter steelhead, but it might not be "fun". The other thing to think about is the fact that you are going to completely wear any fish that you hook out trying to land it. If its a hatchery fish, no biggy, its going home anyway. As you get later into the winter though and more wild fish start showing up, you run a very high risk of killing those fish that you have to let go due to exhaustion. My

would be to gear up a little so you can effectively and efficiently land any fish you hook.