OK, so no tapering for the aprons, and only across the pleats. Got it. Take the pleats in from the height of the rump to the waist, got it. Next puzzlement is with the taper in the apron.

My thought was to start by pinning all the pleats across the backside, making sure I have enough material for the aprons and under-pleats, and then..... That's about as far as I've gotten...