A quick sketch shows that four octagon rooms fit neatly together giving a tiny square center room. This would have a very jagged outer perimeter, and would in practice morph into a nipped square overall shape. The center would be too small to be functional unless the outer rooms were quite large. So I think the outer rooms would have to be some version of trapezoids.
I would group the windows so that two outer rooms shared a window zone, putting the windows at one corner of each room. This would make only four exposed window sections, and longer stretches of uninterrupted wall which could be very thickly bermed. To reduce hard-to-use corners of trapezoids, the corners would be further clipped to give 16 sides to the outer wall.
I would expect the roof to be earth covered for camouflage from the air, with membranes like the wofatis, so steep slopes not required. In fact, steep slopes would be problematic if earth covered; there is a tendency for earth to slide off unless the underlying slope is gentle. 1:12 is the recommended maximum slope for thinner earth coverings (green roofs
) to stay in place. Thick coverings which merge into berms at the base may be able to be steeper.