I haven't had a commercial Alt since I left Germany in 1986. To be honest, although a lot of recipes I see use Caramel malt, I wouldn't do it. Alt should have a dry, crisp, bitter finish. It's not so much about BJCP style as my own memory - sweet alt ain't alt. If it were me, I'd drop the 5 minute addition and add it to the early addition. I don't care what Tinseth or the BJCP says: 2 ounces of 4% AA hops aren't going to give you an authentic (or equally tasty) level of bitterness. Keep in mind, Munich malt is diastatic, so you can replace some of the pilsner with it and cut back on the Caramunich - for malty flavor you can't beat Munich. The next time I brew it I think I'm going to use Carafa or Carared to get a nice medium dark copper color without the sweetness. Don't get me wrong, your recipe would no doubt make tasty beer, but I think it would be a little sweeter and hoppier than the Alt I remember from Germany. Good luck either way, and happy Thanksgiving.