Heat Control with Excel 20

I recently purchased an Excel 20 with the extra stacker. I've cooked on it 3 times using only 2 stacks. I find that I'm having trouble first getting to than maintaining 225-250. I'm sure the first time was due to weather( very windy) How much should you fill the charcoal ring and is there a fuel that is better suited?

I generally use 2 starters full Cocos briquettes ,with charcoal I have no experience (Or it is with grilling)
my smoker stand protected of wind and rain
I have already experienced that in the smoke Chamber it is warmer then that he indicates
I start with a halfly filled waterpan (start with hot water)if he runs well I top up him regular
and then I must regulate the air supply

ive always started with the charcoal ring packed with lump charcoal and a mix of briquettes. Dump on half a chimney of really hot lump, let it burn a minute than close her up. I have the water pan foiled and filled with sand. I than use foil tape to seal up the rings, helps a lot on windy days, makes the temp a lot more controlled. Start with all 3 bottom vents open, at 200, close all of them down to half, wait to hit 250, and run with one open between half and full, always keep the top vent full open, especially with the foil tape, its the only place heat or smoke can get out.

I have been having the same problem.
Recently I was smoking a Brisket and tried something different. I filled my Basket with unlit, then added a chimney of lit on top. I waited 5-10 minutes, then assembled without the water pan. Then it came up to 300, I added the water pan, and adjusted the vents and it came down to 250 and held. This was the first time I was able to get the temp high enough and use the air vents to adjust it down.
I only tried it once, I plan on trying it again next week.
My theory is that the pan is so large that it does not leave much room on the sides fro the air/heat to pass. But if it gets hot without the pan in place first, then it can maintain it when you put it in. Don't know if this is correct, just seems to make sense.
I also used Foil Balls covered with a sheet of foil, not water, when I did this. Will try adding water next time.

Good luck,
Bill