Howdy,Ray.
The goal is to get it coated,sorta like an iron skillet.
Take out your racks,put a little foil on the bottom and poke a drain hole.
Keep in mind you need a drip pan under that drain hole.
Put 6 or 8 0z. any wood in the firebox,set at 250� and let her rip for 4 to 8 hrs.
Throw out the ash,cover the top of the firebox with foil[for easy cleanup}.
5 or 6 oz. of wood will probably be enough for a couple butts.
Spray your racks with Pam[for easy cleanup].
The oven will have about a 25 � temp. swing,like most ovens.Ignore it.
Smokin' would say go at 225�,use your polder and think about 2 hrs./lb.
I like to cook a little hotter,depending on timing.
It won't give the bark like yours,but you can get close.
We like to start them as cold as possible,right out of the cooler.
You can start the unit smoking[about 20 mins.] empty,then open and add the meat.
Unlike your cooker,any time you open the door is about a 30 min. extension in cook time.
Which like you say,"is a good reason not to play with the meat".
The bottom rack,directly over the firebox will cook a little hotter,logically,so if you over load it -you may need to rotate the butts.
The best max. cooking level is figured at 22 lbs.-I think.
I have flattened butts down and cooked 6 at once,about 32 lbs. precooked weight.
Four large butts seem to be a happy medium.
Two of those 15 lb cryovacs from Sam's is about right.
It plateaus between 150�-160�,like most butts and I usually kick it up to its full 250� to get through it.
If you want to add any moisture later on,I just shoot my spray bottle into the vent hole,it fills the cooker with apple juice and drips down through the racks.
I use an obscure rub called Bonesmoker's- heavily,as it it specially formulated not to require mustard as a coating.
You probably won't need it,but it makes a great holding oven at 140�.
Gimma a shout if you need anything.