I hear those char grilled work well! Are you good with maintaining low temp? If not, I used to commit what some consider a sin and cook mine at 300. I couldn't maintain lower temps on my old offset because it was too drafty. Meat cooked faster, sometimes dried out, but always good IMHO.
You can cut in half, but the thickness matters more than the weight for cooking time. There is a great thread by @Gary
, I think, where he showed how it works by cutting a butt in half and comparing cook time to one he didn't. I'll see if I can find it.