@Winz I could prob just fill up the rest of the basket as-is?? Or should I re-pile with one lit chimney on top?
Either would be fine. My approach was to simply fill the basket about 3/4, and dump the lit chimney on top. The key is airflow - as long as you can reduce/increase airflow, the kettle will not get too hot. 51 looks pretty tight so I don't think you will need to worry about leaks. When I did low and slow, I found that I had to close two vents, keep the one under the charcoal at about 1/4 open, and I had to slightly close the top vent to get the right airflow. Worked like a charm.
You might want to think about routing your temp wires through the bottom vent (the one you are controlling) as well to avoid pinch and leaks from the lid.
Winz