There are at least 3 commercially prepared base-mixes for raw (or cooked, your choice) to help you achieve a balanced diet without any fuss or spreadsheets. The Honest Kitchen, Balance IT, and Volhard Nutrition all offer different formulas of base mixes designed to achieve complete, balanced meals with fresh meat added. It makes it very
I have a friend who feeds the Volhard mix + beef, and has for years. Her GSD is healthy and thriving. (It contains some grain [oats]. I can't feed it because it has deydrated chicken liver in the ingredients, and chicken is an allergen for my dog.)
I currently use use the Honest Kitchen's Preference mix + beef. That combo healed a dog with a severe food allergy causing severe GI problems (retal polyps, bloody poop, and worse), and he's in great health now. I don't know anyone using Balance IT but the company is associated with the UC Davis vet school, so it's very reputable.
Here are links:
Volhard Nutrition: Volhard Dog Nutrition
THK: Base Mix | The Honest Kitchen
Balance IT: https://secure.balanceit.com/index.php
ETA: Check with local, independent pet supply retailers about special-ordering THK, Primal, Bravo, etc. Even if they don't stock them, their distributors likely can get them, and most retailers are happy to special order anything their distributors carry. Mine will even get me a case-discount on Bravo if I buy 12 chubs.