I wonder if you could build one using a bullet smoker and get a pizza
stone or unglazed ceramic tile that is just big enough to sit on the
grate, or cut a stone to size, and do it that way and burning wood
underneath. I bet that would work and it would be relatively cheap
and portable and might cost you 100 bucks or so. The only trick would
be getting the pizza in and out, but you might have to cut the
cylindrical portion of the smoker so the stone sits at the top and you
can just drop it on and put the lid on and pick it up easily. I have
a bullet smoker I haven't used in a couple years and am tempted to
give this a try. I really think this would work.