That won't hurt and will give you a bit of lift. When I did the add-a-leaf I stole the long spring from the previous rears, I had already wrapped the upper spring pretty well. The first time I've actually seen a full S instead of just a slight bend.
If you don't have spare springs laying around call Hawk Suzuki, they can send you just the one long spring. They use the lower spring in most add-a-leaf kits as it gives you more lift so they usually have a spare sitting around. I did this when I made my second spring pack.
After I destroyed my second set of rear springs we built a 4-link for the rear. I was looking at making a traction bar then decided it wasn't all that much more to just build the full rear suspension. She handles great now, still use the RUF though.