sweat lodge/rocket stove

I'm planning a sweat lodge and have been looking at these rocket stoves.  Do you think you could build just the fire box out of fire bricks and burn a fire for a while then use the fire bricks instead of lava rocks in the sweat lodge ceremony? 
If it worked you wouldn't have to have a large open fire in your back yard for a couple hours burning lots of wood   Anyone ever poured water on a hot fire brick?

I would just build a pocket rocket or portable rocket cookstove and set the rocks in a wire basket on the top to heat them