My basket is tall too and I've had no troubles. It's the standard 18" Weber Charcoal grate but the way I cut the expando made it turn out pretty tall.
Last cook I had it about 1/2 full, did a 3.5lb. Butt and then a batch of 30 lollies and still ran for a couple hours. About 13 hour total when it was all said and done. I had a couple hours in the middle when I was eating instead of cooking