The Whole30 book has a bbq sauce recipe that uses applesauce for a little sweetness instead of adding sugar. It’s been a while since I made it but DH likes it well enough.
You can do a sugar free dry rub and let it sit on the meat overnight. If doing pulled pork, make a Carolina style vinegar based sauce (mop) instead of a sugary bbq sauce.
This makes great chicken—brine for two hours and the dipping sauce is good on veggies as well—my teenage son loved it:
http://meljoulwan.com/2009/06/09/the-best-chicken-you-will-ever-eat-ever/