I cannot speak for the quality or abilities on a Mainca or other brands, but…
We sell and recommend Talsa Stuffers. We have one here in our test kitchen as well. They do not have a problem running snack sticks on a 12mm horn. 10mm can get to be a little more difficult but can work fine still. A 12mm horn works fine for us and stuffing then into 19mm collagen casings.
Even on the smallest Talsa we offer, at a 26lb capacity and 1.75HP, they will stuff snack sticks fine. I think a lot of the capability just relies on what brand and quality of motor is in the hydraulic stuffer.
If you are doing half deer and half pork, the deer is going to be very lean so just make sure the pork used has a high enough fat content. You can safely use up to about 40% of the total product weight in fat and water (approximately 2 quarts water and meat at 75/25 lean to fat ratio), but that’s the limit I’d suggest. If you still struggle to stuff snack sticks at that point, it may just be a limitation on the stuffer you are using.