Josh,
First of all I'd like to say a big KUDOS for what you've done with just your grinder. I still stuff some sausages with my Hobart grinder as it is much faster if I'm making a large volume of sausage in a natural casing. I found early on that ingredients I added like peppers, onions, cheese, etc. tend to get mashed when done with a grinder. I tried using my 7/16" plate, which is the largest I have, as a stuffing plate (after my meat was ground and mixed) and it still chopped the ingredients finer than I liked. I then bought a stuffer plate (a spacer) and although it worked better, I still wasn't satisfied with the result. A stuffer works best for producing sausage when you want chunks of other ingredients incorporated in the sausage rather than having it mashed into the meat. Just my $.02.
As for the size of plate for a fine texture, I use a 1/8" plate... very fine consistency and no need to double grind.
Keep up the awesome work... and I think we all would LOVE to see some pics of your home built smoke house!!
SMB