Never tried a Boston Butt Mike, but I am going to now. Your technique is very similar to how I do my brisket.
On your brisket. Do you remove the fat before smoking? Myself I leave the fat on and put that side on the top. I feel it allows the fat that does melt to work its way through the meat.
Prepare Meat
Trim fat so it is very thin.* Where fat is exposed make a lot of cuts into it. For brisket or butts trim fat very thin.
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*Dry Cure mix
1/4 cup Morton Tender Quick
1/4 cup dark brown sugar, packed (I use raw cane sugar)
1/4 cup freshly ground black pepper
2 Tablespoons granulated garlic
2 Tablespoons ground coriander
2 tablespoons fennel seed
2 tablespoons crushed bay leaves
I put dry cure on everything and place inside a 3 gallon ziplock (hardware stores have these) and turn it once a day. It will take a week.*
Liquid injection (I don't liquid inject - you'll need to do this on pork loin - dry cure doesn't penetrate this cut)
After dry rub is applied, then add 2 lbs. of Tender-Quick per gallon of water for meat that is to be used within 30 to 60 days. **Bring the gallon to a boil let it cool and mix the 2lbs of tender quick.* Freeze what isn’t used (to keep sterile).* Inject the meat and put inside of those huge 2 or 3 gallon ziplocks you buy at menards.* I’ve got huge syringes and you’ll just need a marinade needle.* The Amount of Tender-Quick pumping pickle to use is 1 to 1 1/2 oz. of pickle per pound of meat.* Put meat in fridge and rotate daily.
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Prep for cooking
Remove meat from fridge the night before, wash off dry rub and soak in water for an hour to remove pickling salts.* Pat meat dry apply dry rub and cook the next day.*
Dry Rub
4 parts ground peppercorns
4 parts ground coriander seeds
2 parts Turbinado sugar
1 part ground onion powder (I leave this off)
1 part thyme, ground
1 part paprika
1 part ground garlic powder
1 part ground ginger
1/2 part ground cloves (be careful with cloves)
1/2 part ground nutmeg
2 parts garlic
½ part fennel seeds
½ crushed bay leaves
Get the bullet goings and put meat in and cook at 200F until the charcoal gone (try at least 10 hours add more charcoal if needed). Periodically add wood chunks. Pull meat, wrap in foil and finish in oven at 325F for an hour.