Yes you can freeze your venison and then make sausage. I do it all the time. Here is how I do it. while butchering my venison I cut out all the fat, sinue, silver skin etc. I cut it into chunks and freeze it. when I have enough and pork shoulders are on sale. I partially thaw the venison( just enough to be able to re-cut it into frozen chunks small enough to go into my grinder)and grind it with chunks of pork and pork fat to get a 20-25% fat ratio. I then add the spices, mix and stuff the sausages. Let sit overnight in the fridge to meld the spices and eat or freeze for later.I do the same with pork shoulders. I cut them into chunks and freeze when they come on sale so I usually have meat ready to go when I have time to do sausage. I would tipically do 50-100lb batches when I do sausage.