My first smoke is done and in the books. No first effort is without error, and so it was with this. Lessons learned...
As had been suggested, these baby backs came from the butcher without the silver side skin, so I still haven't experienced removing it.
I used 3 5/8 oz. sugar maple in three chunks. Certainly not too smoky flavor, but that may be because...
I used too much rub. I put a thick coating of rub on the ribs before vacuum sealing. The next day (today), when I removed the ribs from the vacuum bag, I applied another layer of rub. When the ribs were cooked, they had a fairly thick layer of bark, which wasn't bad in and of itself. However, the strong flavor of the rub overwhelmed the smoke flavor, if it was there. Next time, less rub to let the smoke flavor join the mix.
At about 4 1/2 hours at 235 degrees, I feel the rack of ribs was slightly overcooked. While the ribs didn't fall apart when I picked them up with the tongs, the meat came off the bones very easily, even with just a fork. Next time, 4 hours 15 mins at 225 degrees. This was a single rack of ribs. Maybe more meat requires this amount of time and temperature.
I cut the rack into thirds. I brought in 2 pieces for finishing with sauce in the oven and left the final third in the smoker for an additional 10 minutes. I sauced the two hunks and put them in the oven at 450 degrees for 15 minutes. As many of you more experienced smokers are probably yelling at the screen, "Wrong!" It was way too long. The sauce cooked to black tar. Next time, I'm going back to my "Plan A" and put the ribs back in the smoker for 15 mins.
The unsauced third of a rack was good, and I ate all that meat. The others weren't so successful and went to their grave. I had been planning to brine and smoke a chicken next weekend, but I'm going to try ribs again to see if I can do better. Sorry that I got carried away today and didn't take any photos. I know how you guys like smoker porn.
Thanks to everyone for the information and support.