107 is a good temp. And that culture mix is pretty decent, makes for a nice set.
What texture profile are you looking for? More like a creamy, sour-cream like yogurt? Or one where you spoon and it forms almost a clean break? Or one that just coats the spoon nicely when you stick it in? Or maybe tell me a commercial variety you like? I can dial it in for you. Those additives create slightly different properties. Also, I'm with you, I don't have an issue with those additives, especially for a specialty application like this where you are using raw milk, but if your customers do, you can explain about their properties, and can go the extra mile and process a big batch to use for a few years. If you do it yourself, it's also a lot cheaper. The raw materials are not terribly expensive.