I had some costco butts last weekend, I didn't realize until I got them home that they were boneless butts and I see that Costco usually sells boneless. I don't normally buy boneless so I had little idea how to smoke them.
That was a problem because the ones I got looked like the butcher was blind and I had huge flaps of meat on the ends where they cut the bone out (why would they do that?).
What you (probably) need to do is cut the smaller meat flaps off, because those are going to cook faster, and pull those when they get to 205, then monitor the larger chunks of meat until they get to 205. I left the flaps on mine hoping that if they were pressed together it would cook like regular like if they weren't separate flaps, but those flappy ends were way overdone at the end of the cook, so I was really left with about half the meat that I should have had. Which was ok because I wasn't feeding too many people.