Here is a few pics of some venison summer sausage I made this past weekend use 10lbs of venison and 3lbs or pork fat recipe didn't call for it but I threw in some high temp cheddar.Next time I will add half what I did this time.
I have my first batch of SS in the smoker now with 50/50 venison to ground beef. I am using 80/20 beef so a little fattier than your 85/15 but I got it cheap at Sams. For my regular ground venison I mixed it with 90/10 ground beef from Sams and it was real good in everything I use it in, including burgers on the grill. I will post some pics of the SS when its done.
Looks just right on the cheese. I like to experiment with SS and have settled on half deer meat and half ground beef, 85/15 works best. High temp pepper jack is my favorite.