I have considerable experience with propane jet (high pressure) burners making beer. I really recommend some sort of flame deflector, maybe steel, between the flame and the pizza stone. A ceramic deflector will not radiate the heat it picks up from the flame to the stone like steel will. I'm thinking infrared here. But, I would not put that flame directly onto the pizza stone, a low pressure burner maybe.
Jet burners (also called Cajun burners, high pressure burners, ect.) are nasty beasts (and extremely inefficient on fuel). They are hot, real hot, meant to be shot onto the bottom of a pot full of water. Like you can boil water in a cloth bag or plastic bottle as long as water is present to boil off the heat. Otherwise they will melt an aluminum pot and damage a steel pot if they boil dry. Since the moisture content of pizza is low compared to gallons of water, there must be somewhere for the excess heat to go, infrared radiation is the best here.
Cool project, I'm very interested to see how it turns out. All of the usual methods of obtaining neapolitan temperatures take long to pre-heat, a cajun burner will not take long, for sure.
Thanks for posting,