Those back ribs look almost like the ones I have carved from whole loins. I think there is another section of meat, covering part of the bottom and keeping the ribs unexposed, which your butcher has cut off. I have never seen commercially butchered back ribs with that much meat. Mine weigh in at about 5 lbs on average.
You essentially have a series of attached pork chops or a supersized crown roast. The meat from the loin is lean, so do not overcook them. They are less heat tolerant than spares.
During smoking, definitely baste them. When they feel hot, they are finished. You may want to use a thermometer to gauge this. Whole back ribs fit into my smoker, so I do not cut them. Most people on this forum are partial to the 3-2-1 method, foiling during the second stage. I do not like to cook most parts of the loin, covered with liquid. Dry heat, periodic basting and keeping a close eye on the temperature is how I have done similar monster back ribs. Good luck.