In a large bowl, mix cream cheese, sausage, carrot, spinach and seasonings. Combine well.
Wash pork loin and pat dry. Cut the loin open lengthwise ¾ of the way through. Leave the loin attached on one of the longest sides.
Carefully stuff the loin with the stuffing, and wrap tightly with bacon. Secure with toothpicks.
Place pork loin in a shallow dish and cover with marinade if desired. Cover and refrigerate for several hours, turning the loin occasionally.
Heat grill to 400 degrees. Place loin on the grill, and reduce heat to 325. Close the grill and cook pork loins evenly on all 4 sides. Turn frequently, browning the bacon. Continue cooking and turning until pork reaches an internal temperature of around 150 degrees. (Check temperature in the loin meat, not in the center where the stuffing is.)
Remove from heat and cover with foil. Let rest 15 minutes. Slice carefully and serve.
Notes
Nutritional content does not contain the marinade due to the wide variety of options, and the fact that all of the marinade is not absorbed into the meat. For carb, fat, sodium, and calorie information please keep this in mind.