Combine the salt, cumin, and chili powder. Rub mixture all over roast.
Transfer roast to a 6 quart slow cooker. Add the garlic cloves. Pour juices and both over all.
Cover and cook on low for 8 to 10 hours, or until pork if tender enough to shred easily with a fork. Remove meat to a rimmed platter.
Using 2 forks, shred meat, discarding any extra fat. Return meat to slow cooker, stirring into juices.
If you prefer your carnitas to get crispy bits, spread the meat in a single thin layer on a rimmed baking sheet. Broil, keeping an eye on it so it does not burn, until the edges are crisping to your desired level.
To Freeze: Cool and package in a freezer-safe zip closure bag, removing as much air as possible. Seal and label before freezing.
To Serve: Thaw. Heat through. Serve in a gluten free wrap with your favorite taco, burrito or fajita toppings.