I think the height is OK if you keep the heat low enough. That means your exhaust shouldn't be "too good".. meaning a single 2 inch pipe is causing for a bit more draft than needed. You need to keep a similar circular area but if you split it up into say 4 one inch holes, or two 1.5 inch holes on the side, you'll be able to keep that fire a bit lower.
However having a way to diffuse the heat below also works very well, but make sure to still allow that meaty goodness to drip into the fire.
I use angle iron pieces laid down on a grill grate and it's working great.