There are a few things I recommend:
Do not put the rub on the ribs until immediately before cooking, depending on the salt content the rib meat will leach out moisture wile they sit.
Continue to use the water pan and smoke the "No Peek" method to keep as much moisture as possible in the smoker.
If time allows smoke at a lower temp, 225 even 200 makes great ribs if you have the time to wait.
Do not try to add heat shields, I havent heard of any good results doing it in an SI.