Pork Tenderloin Question

I'm not sure I'm an expert at this, but for leaner cuts like tenderloins I would leave the fat on.

After you've cooked it to internal temp and then let it rest, the fat should pull off easily.

Also, for center cut loins that I've done (and a few tenderloins) I always wrap in foil around 140 internal, then let it go up to 162...and then remove from the smoker and let it rest in the foil. This helps alot against drying out the meat and if the I.T. is 162...is will raise to 165-167 while it rests in the foil.

Of course, the other school of thought here is that these days you can eat pork that isn't considered well done...you could eat that at 155 - 160 with no problems. Personally, unless it's a good cut of beef - I take everything to 160-165, but some folks are a little more adventurous!
My $.02

Fats flavor, and i think it helps a bit with keeping moist. you can trim it of easly after it has been smoked, just don't over cook it, 160* internal, i pull it a little before that , but the food police may get me nfor that.

I would leave it on. Or I should say I do leave it on. It adds a really great flavor to the loin. I don't take it off after I cook it either. I take mine to internal 160 and cover and rest. As a matter of fact. Throw some bacon on tip of that sweet loin. Don't be sceard. Rub some rendered bacon fat on her halfway through.

Just be careful of overcooking. It is really easy to dry out a loin and especially a tenderloin. Been there and done that. Let us know how it turns out.