Harvest Weiss

I have a small crop of hallertau hops that should be ready to harvest soon, so I am prepping this recipe.
I am doing this one brew-in-bag.
2.5 gallons water, heat to 120 deg F and mash in.
Heat to 113 deg if necessary and hold for 5 min.
Heat to 122 degrees and hold for 30 mins. Once the wart reaches 122 deg., remove 2/3 gallon of wort for decoction.
Heat the decoction to 162 deg. And hold for 5 mins then boil.
After the main mash has rested for 30 mins, add the boiling decoction back in.
This should raise the temperature to around 150 degrees.
Hold at 153 for 45 minutes.
Heat slowly to 162 degrees and hold for 5 minutes
Add 1/2 gallon boiling water. This should increase the temperature to around 168 degrees.
Hold for 5 minutes
Sparge with 170 degree water until 4.5 gallons total volume.
Boil for 90 minutes
Add hops at beginning of boil. I put them in a hop spider. As stated above, I am using fresh hops. I am assuming that the calculator assumes dried whole hops, which is why the calculated IBU is so high, but i am guessing i will end up around a 10 as 5 oz fresh should equal about 3/4 oz. pellet.
Cool and pitch.
I am doing traditional open fermentation for this batch.
Seal fermenter with lid and airlock and store in a clean, dark, non-drafty area.
When fermentation really kicks off, carefully remove the airlock and lid and cover with sterilized cheesecloth to prevent dust and insects getting in.
Open ferment as long as you care to risk. I am planning on 4 days. Re-cover and airlock for balance of the fermentation.
I am going to shoot for around 4 VCO2.
I am going to bottle condition with speize and lager yeast. I will update with specifics when I get there.