Don't skimp on the fuel, I think you are on the right track there. Set it up as if you are doing a 12 hour brisket every time. The unused coals will just be used next time. Also don't skimp on the lit coals you add, make sure it is at least half a Weber chimney. Most people need to use a full lit chimney and the door propped open just to get much above 300. I assumed you are looking to keep 225 to 250, that is always what I used the WSM for. If you don't give it some fire to work with the graph will look like the Grand Teton's. As long as your WSM and fan are fairly air tight it should work great. Good luck!