Sorry it took me so much to answer: I was very busy last week.
Here it is a very simple sketch of what I am going to do: as you can see I made a detail of the side hip region from the outside and the inside (not considering the lining).
As (I hope) you can see I'm going to put interior boning channels (I need them since there is only one layer of coutil and I decided to put the on the inside because pre-made boning channels covered with satin bias comes out a tad too wide for my taste), and fake satin bias boning on the outside. The leather panels are going to be sewn with one another and then applied over the normal panels: to fix them I thought to sew a continuous line on the bottom of the corset (since there is no boning-crossing problem there), and to sew in between bones on the top of the leather panels. To cover the edge of leather (and the sewing) I am going to hand sew a satin bias strip over the edge of the leather: I thought and thought about this but I guess that hand-sewing is the only way here, since there are inevitably bones to cross...but every suggestion is welcome here!
I don't know if the sewing on bottom and top of the leather hip is going to suffice: I fear that may lead to some wrinkling of the leather... do you think I should double sew on the sides of the leather panels joing too?
In the end this is the worksheet I have devised:
1 Flatline fashion fabric (green dupioni) to coutil
2 Preparing busk and Eyelets panels
3 Sewing panels together
4 Put on internal boning (and waist tape)
5 Put on external (fake) satin boning
6 Sewing leather panels together
7 Sewing the entires leather hip panels on the corset
8 Hand-sew the satin strip over the edge of the hip panels
9 sewing lining and attaching it to the corset
10 sewing bias on top and bottom
Does this make any sense?