I have only smoked salmon once, and it was in my SI3 with auber.
I had bad results, as I also planned on pulling it at an internal temp of 140F. My problem was, from the time it hit 140F, to when I got inside, grabbed a cutting board and came back out and opened the smoker door, IT registered 150F! Too dry for my tastes at that temp.
I would baby sit the last few degrees and pull it immediately.
As far as temp, smoke and the white stuff...
I went 1 hours at 120F, 1 hour at 140F, 1 hour at 160F and 1 hour at 180F.
I had read that cooking too quickly (too high a temp) is what squeezes the white stuff out.
I was basting with sauce every hour and there was white stuff present.
You can brush most of it away while basting.
Also, I didn't get any smoke at 120F in the SI3. Smoke started at 140F and really kicked in at 180F.
Good luck.
One last note...
I had so much of the salmon in there that it filled a rack front to back, side to side. The basting and salmon jus got all over the smoker and rack slides. Afterwards, the smell drove me nuts and turned my stomach. So much so, I had to strip clean the smoker; first time ever.
I believe in seasoning the smoker. After so much pork, beef, chicken and turkey, that smoker was so well seasoned, I didn't have to use a rub on anything, and it still tasted good!
It really hurt to strip it, but that salmon smell drove me nuts.