none of my dogs will eat veggies or sweet potatoes if given the opportunity. I usually cook the sweet potatoes in a crock pot, then add the veggies and grind it all into a liquid mush in a food processer. That gets mixed with ground or finely chopped meats and either fed with the meat still raw, or cooked like a meat loaf.  If they want the meat, they have no choice but to eat the veg/potatoes. I don't actually feed much carb or veg. One small sweet potato per week per dog plus a few random assorted vegetables. Many folks feed no veg or carb to their dogs and have no problems.
Don't forget you need to add calcium if you're feeding boneless meat.