Dutch oven, distance from the floor?

Hello dear community,

My Dutch Ovel is primarily used in a gas grill, but now I'd like to use it over grill briquettes (grill cubes, to be precise). My question is: Does the pot have to sit directly on the cubes? I'm worried that they wouldn't get enough air circulation, so I'd rather place the pot on a rack. The rack is 6 cm high, and the cubes are 4 cm thick. Will the 'lost' 2 cm still allow enough heat to reach the pot from below?

Thanks.