Bacon fat is 100% appropriate in my book. Doing a brisket right now so maybe some beef and green chile tamales in the future? I like the muffin pan and paper inserts idea.
I've heard some people use those thin foil sheets too. So far the corn husks work for me though. Usually my tamales stem from leftovers of grilled or smoked meat (mixed with appropriate chilies, onions, tomatoes and spices), or leftovers from tacos (basically the same thing, grilled/smoked meat plus veg).