Sinew would definitely prevent it from lifting a splinter. On a bow that length, even at a 30 inch draw length you would not actually begin "loading" the sinew, so it would add more weight to the limbs than it would add to the cast of the bow. I agree with the others that very thin rawhide would be your best bet.
Goa with goat, or antelope. If you have a deer rawhide, the belly side will be the thinnest. The backs of deer can be a little heavier than you might want. In the P.A. Magazine classified advertizements there is a guy named Michael Foltmer out of Colorado and he sells really large antelope hides for about $40. You can back about 6 bows for that price. Or you can buy backing strips from him for about $20 if you don't want a whole hide.
