I simply Minion the start (I always do), load the fish in immediately when assembling the cooker (I always do that too) and, in this case, cut the vents when the temps get into the mid-200s. I let the temps drift down - I am not looking for stabilization - and by the time they drop the fish is done. You could, however, simply target a low/slow temp of, say, 250, using water or whatever in the pan if you wish, and simply smoke till done to your liking. Remove, rest a few, serve; or wait till room temp then serve; or chill after cooling and serve chilled.
For the slaw, halve a cuke lengthwise then scrape out the seeds by running the tip of a teaspoon down the center of each half. Grate the cuke halves using a medium grater into a sieve, toss lightly with salt, then allow to drain for 30 min or so. Grate a few radishes with a fine grater then toss together with the drained cuke; chill. Before serving, adjust salt and add a little white pepper and, if desired, a pinch of sugar and a few drops of lemon juice. (Also good with a little minced fresh or dried dill leaf. I skip this if using dill on the fish or in the sauce though.)