Congrats, dude. I've done ribs a few times and still haven't been entirely pleased with the end result. Just not getting as tender as I want them. I've let them smoke for longer than my expected cook time, they seem done to me by the flex test, geting a lot of bend and the skin starts to break, but they just haven't tasted as tender as I want them to. Haven't tried them in a while, need to give 'em another go sometime soon and make a strong effort to really let them go longer than what feels right.
Why did you think you needed more rub? Not as much flavor as you wanted or didn't get much of a crust? Did you finish them with sauce or only a dry rub Memphis style?
Could crock pot the ribs first to break down the connective tissue, then put it on the smoker.
I'm trying to invite myself over next time you smoke meat.