Remove the tri from the fridge, say, now. Sprinkle with salt all over. Use an amount equivalent to what you would use were the meat already cooked and had been just served to you unsalted. Allow to rest on a plate on the counter a couple hours.
Make your rub of choice. I'd go with something like 1 T each granulated garlic, granulated onion and white or black pepper, 2 t each thyme, sage and a ground chile of your choice, 1 t marjoram, 1/4 t ground clove. When you get the cooker ready to go apply the rub over the salted meat's surface.
Smoke ~ 220-250? to an internal of ~ 120?. Either raise the temp of the cooker dramatically at that point or move the meat to direct heat. Sear, turning frequently to prevent scorching, to an internal of ~130-140, depending on your taste. Remove; rest, tented, 15 min; slice thinly against the grain and serve.