So here is what I do for large batches...
I coarse cut the meat and fat into strips that will fit in the grinder. Chill to below 32*F, then I grind with the largest plate I have, which is the stuffing kidney plate. This cuts the meat into 3/4-1" chunks...perfect for mixing the seasoning and salt. For the smoke sausage- we mix, then hold in the double door refrigerator overnight to allow the meat to chill below 32*F. The next day is final grind through whatever size plate you want. We use a 6mm plate for smoke sausage.
The larger 3/4-1" chunks are a breeze to feed into the grinder and the grinder helps with protein extraction during the grinding process with the meat having already been salted....takes much less mixing to achieve a great bind. Which is another reason why I have no need for a dedicated mixer.....I let the grinder do most of the work for me.