An old man turned be on to butter and bird awhile back. When he smoked any bird, he would put a stick of butter for a turkey and 1/2 stick in chickens. That's what I did with these birds. It seems to penetrate all over while cooking. I do inject those Cajun fried turkeys though.
Weber WSM, Weber GA, Weber Spirit S-320
Charbroil Oilless Turkey Fryer
Wife LuzziAnn 1956 model.
Maverick ET-732, Superfast LSU Purple Thermapen & ThermaPop, Party Q