Damper full open will evacuate moisture and dry the casing enough to begin a smoke cycle with good color and smoke adhesion. This a good thing
However if you insist on doing the entire cook cycle to 152F in the smoker then critically moisture is needed to finish with a tender casing.
Some meisters will cold/warm smoke for flavour and then boil a pan of water and place on the smoker element for the cook phase.
I usually poach separately for better control and a disdain for black rain
Casings are a natural product and can vary quite a bit in tenderness due to age of animal and diet.
But generally
a good soak with repeated rinsing will soften salt toughened casings.
The old adage about dropping a frog in boiling water applies especially to casing
Acidification will tender casing, but more than 10-15 minutes can result in major splitting when stuffing.
When poaching sausage to cook-always start in cold water and SLOWLY bring to a max water temp of 170F and a IT max of 152F - but 145F-148f better.
Cheap, durable and reliable
http://www.ikea.com/ca/en/catalog/products/80100406/
I use the Ikea Fantast