Well, this was partially successful.
I smoked some salmon first, while the smoker was coming up to temp... I've found that I can get longer cook time with a more tender, moist fish if I add the fish when I start the smoker, and let it cook while the temp comes up. In this case, the fish went on at 100, cooked for about an hour, at which time the smoker was up to 190.
Unfortunately, the temp didn't come up as quickly as I anticipated when I added the pork, and only hit a high of about 215, and that was at the end of an hour.
The internal temp was at 140 at that point, but the tenderloin never developed a bark, or even darkened up much. I pulled the meat, heated up the grill to about 550, and did a reverse sear, and also brushed it with BBQ sauce and let that cook for a few minutes.
Visually, it was disappointing, and there wasn't much in the way of a smoke ring. The good news is that it was perfectly pink throughout, and still very juicy. It was tender and tasty, with a subtle smoke flavor.
It made a decent meal, but I want to take a second shot at this with a properly heated smoker.
Thanks for all the input!