Thoughts, feedback, and suggestions would be really helpful as I'm trying to get better with every smoke I do!
Most BBQ sauces are high in some form of sugar. Basting the meat with it, you ended up with burned on sauce that can be very hard. That's more than likely what happened with yours. Dry rub is ok, it usually has sugar in it as well, but it won't burn up like sauce will. Basting it with sauce the last half hour would be ok, you just have to keep turning it or put it off in a cooler side of the grill (indirect heat)
Crackling Pork...... You added some smoke, it sounds delicious.
It was total awesome sauce!