Stan could tell you better than I, but you also need sufficient clearance above the catalytic. When I had a Wave 3 I tested it in stealth mode and never really got comfortable with it. My heater was mounted on the wall (not sitting on the floor - I'm not sure where it'd fit on the floor in stealth mode anyway) so I tried a fan moving the hot air away from wherever it's gathering right above the heater. That worked to keep the ceiling/canvas from getting hot, but I just wasn't comfortable with the cramped quarters - even set up a little "cage" to keep my sleeping bag from hitting the heater, which was probably overkill. Ultimately I figured I'd never get any sleep worrying about the heater, and we switched to a furnace anyway.
Plus what schunkb said...