I’ve used a pizza stone for some decades, but on thinking of doing a pizza party, I thought I’d finally buy a pizza steel (on the way). But I know there is a lot a physics in pizza cooking… My ideal is Neapolitan style. I’m wondering, as cooking for a group probably making 6+ pizzas, if it works well to preheat the baking surfaces and cook at two rack levels simultaneously. The host’s oven might max at 500-550 degrees.
In theory it should work, the part to figure out will be how the two levels cook differently and how the higher stone/steel may insulate the lower one.
I might put the steel on top - because in theory I think it will radiate more heat than the stone, thus helping the bottom pizza cook more evenly.
If the oven has convection, I’d use it in this case to increase circulation between the stones.
Last thought - I’d have two peels for this party. My gut is telling me that the bottom one may cook the crust faster but the cheese might not melt as quickly - and the top one doing the opposite (cheese browning but crust not quite done). You may find that 1/2 way through you may want to switch the pizzas - and two peels will make that much easier in a party situation . . . . but very curious how it goes if you do it!!!
Thimes’ theory echoes my experience doing this in my home oven - you’ll probably need to rotate. I would put the steel on top so the reflective surface helps to cook the top of the bottom pizza, but I still think you’ll be rotating (or at least sticking the bottom pizza under the broiler briefly). Also, the pizzas cook a little more slowly overall than they do in an oven with just a single steel/stone.