Thanks SpanishCastleAle, that helps a lot. So does something like this sound better?
1. Heat 22 Qt water to 144º, add grains (11.5 lbs) and stir well to achieve 135º
2. Decoct 7.5-8 Qt thick grains, raise temp to 158º, rest 10 min, then boil for 30 min
3. Add decoction slowly back to MLT to get 153º without going over, rest for 60 min
4. Decoct 4.5-5 Qt wort, boil for 10 min, add back to MLT and rest 10 min
5. Sparge with 3.4 gal 170º water, or enough to collect 6.5 gal wort