When I have the sticky butt problem, I have a very large spatula I use. It's big enough to scrape the entire butt off, even when it wants to stick a little.
-Man, that sounds seriously wrong.
Another option is to lift it and have a helper standing by with a spatula to scrape off any parts that stick. You could also cook to a slightly lower IT to avoid it completely falling apart on you just from trying to pick it up. Unless that's the texture you're going for. Personally I prefer a tad more chew in it than that when it completely melts. I want it to shred nice, but still chew like meat. But that's just my personal preference.
One other thing I've thought of is not rubbing the bottom. If there's skin on it, the rub is going to waste anyway. And when there's no skin, I usually scrape off the fat layer on the bottom. My experience has been that it's the sugar in my rub that makes it sticky.