Indirect Grilling

All, I would like some advice on indirect grilling on my YS640.
I often do burger/dog cooks for our church youth group. I may do 50#-60# of burgers plus dogs in one cook. I have previously done this on an old gasser that the church owns but would like to try using the 640 because of the larger cooking surface available to me.
I have the two piece diffuser and 6 grill grates so I can set up about any way I need to.
I am thinking diffuser in with the door in for ease of cleanup afterward, baffle set "center" to try to keep temps close to equal across the grill grates and a 425F - 450F set temp.
I know the factory diffuser is not recommended above 400F but I'm not clear on the guidelines for the two piece with door in. Herb has said, I believe, with the door out "sky is the limit."
Thought and suggestions?
I often do burger/dog cooks for our church youth group. I may do 50#-60# of burgers plus dogs in one cook. I have previously done this on an old gasser that the church owns but would like to try using the 640 because of the larger cooking surface available to me.
I have the two piece diffuser and 6 grill grates so I can set up about any way I need to.
I am thinking diffuser in with the door in for ease of cleanup afterward, baffle set "center" to try to keep temps close to equal across the grill grates and a 425F - 450F set temp.
I know the factory diffuser is not recommended above 400F but I'm not clear on the guidelines for the two piece with door in. Herb has said, I believe, with the door out "sky is the limit."
Thought and suggestions?