That's a lot of IDY - what's your fermentation time/temperature?
I'm not familiar with the oven (do you have a link?), but...
Have you tried high/low stone positions?
An emergency dough made with HG flour will tend to be tough.
Balling too close to the bake can make it tough (and hard to open).
A lower-hydration dough will bake and brown faster - less water to drive off, AOTBE.
100% Flour (13% protein)
2.2% ND Malt syrup
Salt was to taste; oil and malt are "the same so I can't screw it up".
I do a 2-4 day cold bulk fermentation, ball the night before, and temper for a few hours before the bake.
I've used this dough successfully for bakes ranging from a 20-minute Detroit at 440F (I didn't feel like re-firing) to wood-fired NY (4-7 minute bakes, from 650F down to 530F, with or without live flame), and in a GE home oven.