St Louise are full spares cut down so they cook more evenly.
Since it's the next day, my thoughts are for your next cook.
Take good notes. You're new to the smoker and ribs so notes will help your learning curve.
Weigh the ribs. After trimming, they could be 2 lb or 3.5 lbs and that WILL matter on each cook. Note the weight in your log.
By the time you're at 3 or 4 hours, the woods probably already gone, so worry more about losing heat when you open the door.
Note how many times you open the door. If you leave the door open, heat gets out.
The best way is to have some great gloves, pull a whole rack out and shove the door closed. EACH TIME you open the door it will add 30 min or more if all the heat gets out.
There are lots of methods for checking doneness, but if you learn the toothpick method, you'll get a lot better. After a while, you'll be able to determine doneness successfully.