Hook, It looks like you are doing what I was gonna suggest. Use turkey breast meat.
If you do a 10# batch use 9# of ground turkey and 1# of ground pork butt. If thats too lean then go 8.5# & 1.5#.
10-15% fat content just isnt that bad, and alot of that renders out on the grill.
If you pan fry sausage use extra virgin olive oil. Better yet put it on that broiler pan that came with your kitchen range and broil it.
Personally, if I was told I had to cut back on fat I think I'd keep my sausage at the level I like (maybe just dont eat it as often), and cut back fats in other foods.
Its the fat content in food that we dont associate with fat that causes most of the dammage. Just read all the labels on the cans and boxes in your pantry.
Just my rambling thoughts.