I actually used my own gluten-free flour mix and baked some of Ann's banana bread. (No xanthan gum included.) I baked it in mini loaf pans for just about the same amount of time as the recipe called for, covering it loosely with aluminum foil the last ten minutes or so. It was a grand success!
So here is the gluten-free baking mix recipe I have. (You can even enjoy licking the spoon after pouring the batter!)
1 cup white rice flour
1 cup tapioca four
1 cup sorghum flour
1 cup coconut (or almond) flour
1 cup corn starch
I mixed a double batch and have it and the leftover flours stored in the freezer.