Deck Help

So I want to extend my patio (slab) with a deck, and I want to use Trex to surface it. My problem is, I also want to build a brick wood burning firepit on said deck. How would the OB go about doing this in the safest/least injurious to my deck surfacing way possible?

My initial thoughts are to pour a small slab at whatever height my deck will be at, build the firepit on the slab, then build the deck around the slab. Either the size of the firepit or a little bigger, and I could put slate around the firepit to make up for the distance between the Trex and the pit. I could put vents on the bottom of the firepit that can open and close to clean it out, but they'd obviously have to close effectively to prevent embers from falling out onto the Trex.