Small Size Grill Set Up

[Ash3751]

Good Evening,

 I have a question on the best way to set up the charcoal side of my BBQ. The actual adjustable coal shelf only measures around 33x33 cm. I tried the snake method on it last week, cooking a small pork shoulder (that tasted great but ended up a little dry), with the coals going down one length of the shelf but it seemed to burn out quite quick and I had trouble keeping a steady 225 it was constantly over the 250 mark. I used about 10 coals to start the snake off and had both vents open and adjusted the temp using the top and bottom vents but could'nt steady it. I have attached a picture of my set up. the meat went in the top right corner as that's where the exhaust vent is and I scattered wood chips along the length of the snake.

 I'm thinking that maybe I used too many coals to get the small snake started and it burned to hot too quick?

I may try to use one less drip pan and have the snake coming across the front of the coal shelf also and only using 5 coals to get the snake started?

Any one able to give some pointers?

All the best,

Ash