WELCOME ABOARD-- CaptFrank.
It seems that all the "consumer" smokers have the same problem. Blasted firegrate almost lays on the floor of the firebox. Any fool knows ya need 3 or 4 inches under the grate for airflow. I guess the engineers never used a smoker.
The Brinkman owners will chime in later- everyone is cooking today.
Some guys use firebricks to raise the fire grill.
This can also be fixed by buying the shelf mounts from CharBroil and bolting them into the Brinkman. Part #25601012. Mis-labled in the CharBroil literature as "adjustable shelf", but it is really the 4 mounts with a hardware bag. Costs about 10 bucks or so. Phone is 1-800-232-3398
Then, move the cheapie grate up to a shelf mount. May have to lay rebar or other metal strips under the shelf if it is not wide enough.
I'm making a grate out of 3/8 rebar with 1/4 inch spacing which should work a bunch better than stock. Not done yet.
Long term fix- Brother Big Al makes an awesome basket for the Brinkman and the Bandera. He is between production runs right now while he figures out a new price. The price of steel has gone outa-sight!
The ash pan will be big enough if you burn all wood like some of us do. Ash is about nothin' from wood. Charcoal will leave a pretty good pile, but if it is 3 or more inches below the firegrill, you can just deal with it after the burn. Should be a minor problem.
While you wait for better answers, hop into Cattle Call and tell us about youself! We can swap lies about boat driving over there!
Also, peruse the Bandera 101 document! World of info there!
TIM