I believe the standard percentages are 80% muscle meat with fat, 10% organ ( not more than 1/2 liver ) and 10% meaty bones.
Are all the rabbit, fish, duck, beef, turkey, lamb, goat, mutant, and a little bit of chicken whole or have bones in them? If not, the bone content might be a bit low as you describe the diet. Yes, too much protein and too little bone is probably not the best. I wonder if the loose stool your dog gets from bones is more the cause of the marrow. If you are giving marrow bones as the bone requirement, I might find a different type of bone....usually non-weight bearing bones as they tend to be "softer" and easier for the dog to deal with and less risk to their teeth. If you are reluctant to feed the proper bones to your dog, see if you can get some minimally processed bone meal and incorporate that into his diet.
Most always, dogs develop a very solid stool when bone is part of the diet...once again...the only loose stools I have ever seen from my dog eating bones is if it marrow bones....the dog eats the marrow and leaves most all of the bone...If you are feeding your dog too much bone their stools will be whitish in color and very dry.