Hey Tom, does it work to inject something this thick - the sauce is about like catsup?
Have tried boneless loin this way in the past. It's better for slicing and eating cold, but butt seems to have a bit more "porky" flavor. I do usually bone my own and trim off a lot of the fat. Cooking to a higher temperature renders out some, too.
My brother occasionally makes ribs in his kettle grill (indirect method) using the same sauce, too, minus the tenderquick. Tasty, take a little minding to prevent burning.