Another mailbox mod question

[smokerlover]

I have  a Great Outdoors Smokey Mountain Pro Series I'm doing the mailbox mod to. Should I have the inlet to the smoker above the water pan? I was going to put it just below it, between the burners , but which way is best? Any quick help would be appreciated. I'm ready to cut the hole in and I only want 1 hole

 

[smokerlover]

Its a smoke hollow pro series.
I need help!!
It'll produce smoke fine until I light the burner. It immediately pushes the smoke out the holes in the mailbox door - like a reverse flow. I have both side vets open and the chimney open. I crack the door and it starts smoking in the smoker again.
I have the 3" hole in the back of smoker approx 12" above the burners and 16" above the side vents. I have no restrictions on the airflow to the smoker.
I have (3) 1-1/8 holes in the mailbox door.
If I shut the burner off it'll produce smoke again.
I've been bragging about this mod to friends and plan on making some ribs and quarters this weekend. What do I need to do?
I don't want to turn my smoker into swiss cheese with holes.