I wouldn’t. The reason perlite (and here I agree with @Peter on that material versus vermiculite) works underneath is that, again, your firebrick in the floor is going to be refracting heat back up into the oven, and convection is already driving most of that heat up and away.
In the hearth void, you’re providing a stable surface that is reinforced above and below. Above, though, your stucco is subject to that Ohio cold. I am concerned that two structures on top of the fiber blanket (the perlite shell and the reinforced stucco) are going to expand and contract dissimilarly, leading one to fail.
I think, since you’re only building this oven once, that because of your climate you should go the extra step and add another roll of ceramic fiber blanket. It won’t matter in the summer, but it will make some difference in the shoulder seasons, and definitely in those winter days when you just want to fire up and eat like you did last summer. 