I liked your general idea, but I wanted to put my own spin on things. I made a 10 gallon batch. I used 16lbs of leftover Holloween pumpkins that I roasted. My 10 gallon cooler will not hold all the grain and the pumpkin, so I mashed the pumpkin up and boiled it separately. I got 4 gallons of pumpkin wort that I added to the boil. I used a strainer to get it all out. I added amber Belgian candi sugar (2lbs) to the boil.
I cold conditioned the beer after fermentation, and it cleared up nicely. The spices are there but what you taste is malt and pumpkin, not an overwhelming spice profile. My suggestion is to load up the pumpkin like crazy.
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