How big of a pizza can you bake in a home oven?

It is once again Christmas time, and once again I'm volunteering to bake pizzas on Christmas eve for my parents and in-laws.  Last year I baked a series of 7 personal-size pizzas on three stones in two ovens, with generally successful results.  This year my mother-in-law has requested/suggested making somewhat larger pizzas.

Now, in The Bread Bakers Apprentice (and probably in his other books), Peter Reinhart notes that pizzas larger than personal size don't bake well in a home oven.  I took that to heart, and so I have only ever worked with ~300g dough pieces, which produce ~10 inch pizzas the way I stretch them.

So I'm wondering if anyone has experience with baking larger pizzas at home, and could advise me on how big you can get before the crust doesn't bake so well.  Bonus points if you know offhand how big to scale of a dough ball in order to reach that size.

So that you know my parameters, I'll be working with my own 15x17 inch rectangular stone, plus my in-laws' 14-inch round stone, plus possibly a third rectangular stone.  Last year I had two rectangular stones in the main oven, with one pizza baked on each, plus the round stone in the microwave/convection oven combo above.  If I were making larger pizzas though, I might go ahead and skip using the convection, as it doesn't get nearly as hot as the main oven.  I'm using a slightly modified version of Peter Reinhart's Neo-Neapolitan pizza dough from Artisan Breads Every Day.

Any advice appreciated (although now that I think about it, I may just go ahead and bake a largish pizza for lunch tomorrow and see what happens...)