Dome insulation vs cooking surface trade

[nwaring]

Hi,

I’m in the final stages of planning my Pompeii igloo style oven

I’m hoping the community can provide guidance on the depth of insulation the dome. I will be using 128kg/m3 ceramic fibre blanket.

I’m limited to 1.2m width of final oven.. should I use 50mm of blanket (giving 82.5cm.cooking surface) or is there a benefit of using 75m of insulation which reduces the cooking area to 77.5cm?

Thanks in advance!