Well, I don't know how many fishies ya got , but use one as a sacrificial tester. The thick fillet chunks we do usually go for 4-6 hrs, on the cooler side of the smoke. Like 150-160 instead of the 225-250. Fish smokes/cookes very easily and the biggest mistake most folks do is over smoke it. Depending on your taste, some like it soft and squishy almost spreadable, and others like it like a ham like consistency. Myself I prefere the softer/oilier just past the flaky stage. Would be a shame to oversmoke those tender lil steelheads/rainbows.
The ultimate texture IMHO is when you can spread a chilled whole trout from the belly and it breaks at the backbone, peels back and rolls off the skin. Ultimate heaven.
I would shoot for 2 1/2 -3 hrs, check your sacrificial fish. If it flakes good, and the meat looks to be the same color all the way through, it should be done. Remember, fish like all smoked meats , taste alot different when chilled then when they come off the smoke warm.
Here is a lil secret I use when doing salmon, and trout. Just before I take them off the smoke, I make up a little sweet baste. 1/4 cup of apple juice, 2 tbsp. brown sugar, 1 Tbsp honey. Mix it up good and brush it on the fish( inside, around the ribs and backbone) while it is still warm. It makes a nice little coating, and if you do it warm, it will drain off a bit so it won't be too sweet.
Let the fish cool for a couple hrs, and have at it. Let me know how you like it.
Note: you mentioned these fish were 2-3 lbers, So I think my time conf. is about right, but may need to be tweeked. I am used to doing the bigger(thicker) pieces at 4-6 hrs.