Not surprised as virtually all large brewers keep their recipe specifics closely guarded secrets. It's also likely that hops blends are used to help with consistency and ease availability problems. So unless you find access to some locked away stash of Spaten recipes I'd suggest trying something to get you into the general range and then adjust as necessary on subsequent batches.
To me Spaten is more or less a modern version of Oktoberfest, based on Vienna malt and lighter in color than older Munich-based brews. German noble hops are a must and your favorite Munich/Southern German lager yeast is a good place to start. The White Labs WL-820, 838 and 833 will all work nicely and should be widely available. I like a blend of German malts and might start here with a majority of Vienna along with good amounts of Pilsner and Munich I. A little light crystal or Carapils is optional but I like some dextrine malt combined with a low mash temp (55C/149F) to get a dry, clean finish while still having some good mouthfeel. I also like a decoction mash here so if you're up for it give it a try although it's not a requirement.
Here's a sample five gallon US recipe to use as a beginning outline:
7 lbs German Vienna
2 lbs German Munich I (light)
2 lbs German Pilsner
.25 lb German CaraFoam
1.5 oz 3% AA German noble hops (Hallertau, Spalt, etc)
This should come in about 1.055 OG and 22 IBU with a close to Spaten color.
