I know this is an old post but wanted to add to it. I make goose sausage every year, I mix it 50/50 with pork shoulder, and sometimes add 2lbs of pure pork fat, to equal 30lbs. It turns out great!
Bear, the problem with adding fat to jerky is that fat will go rancid, IMO jerky should be made with very lean meat and kept that way. If you keep it frozen or refrigerated it should be fine, but if you are in the sticks for a week and need to have food stay good keep the fat out of your jerkey.