SeldomInn: Using the tube only doesn't add too much heat. I only smoke for 1 hour before turning fan and heat on and then remove tube after 2-3 hours (taste test determines when there is enough smoke) . I usually turn smoker temp up to 150 for 2 hours. Then turn heat up to 180-200 and keep it there until done. I do make a foil bridge to tip one end of tube off floor of smoker, it will keep burning that way.
This batch took 10 hours to get dry enough where I felt it was done.
Pork Belly: I use a jerky fan I made from pvc and a 120v cooling fan. Details are in another post "Making Jerky for first time in SI #3". I agree with low heat. Keeping the heat lower seems to leave it tender. I also use #1 Prague Powder for safety's sake.