Never done it myself. Maybe what I have had was not trimmed well. Even trimmed well I am surprised it makes good stock. Bone marrow is basically fat. Maybe I will get adventurous and try this myself with the next deer to hit the ground.
Since it makes good stock probable be best to trim off all the larger pieces of meat and set aside. Make your stock then turn it into stew. I never cook my venison long in stew. I get my stew to the point of about done. Quick pan fry on the venison and let cook at most a half hour in the stew. Never encountered any venison that needs to be stewed unless your using meat from the shanks. Trimmings off the loin are without a doubt going to be tender.
