I put a sheet of tinfoil at the bottom of my oven to catch crumbs because I cook pizzas on the rack all the time. This is ruining my pizzas though, because when the top is done the dough is still gooey. Should I raise the pizza higher? Use a different material? I donno if a pizza stone is an option... I often get papa murphies pizzas which say to cook in the tray and are usually quite large (16"), but am willing to try breaking the rules if someone has some good experience with other methods.
I would probably go ahead and get a pizza stone. Even if you don't want to bake your pizza on it, you can just keep on the floor of your oven (unless you have exposed coils/burners there, in that case, go with the lowest rack).
The pizza stone is easier to clean, and as an added bonus, it'll improve your oven by keeping a more even temperature in there.
Tinfoil is reflective so it bounces the radiation part (probably not the convection) of the heat transfer back to its source. That's why tinfoil is used to protect meats from browning in the oven and also the reason why the thermos flask inside walls are mirrored (or plated? ... my English is awful)
You may experiment with a thin sheet of another (probably ferrous and non-reflective) material, taking care of heating it in the oven very well before putting your pizza in.
This is an example of the correct use of tinfoil,
clearly opposed to your objectives.
In my house we use a pizza stone all the time. Pizza, biscuits, bread. It's the only way to get our oven to cook the top before the bottom side is blackened. It cleans very easily too. Much like cast iron, it becomes seasoned and is as good as non-stick by now.
It will take longer to cook. Where the time on pizzas before was roughly 13 minutes and the bottom would be the most cooked, now it takes 16 minutes and everything is cooked evenly.
Coincidentally, I just saw this question after putting a pizza in the oven. 9am is a good time for pizza.