I've restarted the project. Thanks to KBenco's tip off, I've now read Susan Khalje's article in the latest American issue of Threads and have a better idea about boning the undercorset. I also gained useful insights from Gorgeous Fabrics lace bustier tutorial. I'm now using muslin (I didn't have any more fine tuille) and rigalene boning from Tessutis. I've made the casings from biased binding and ribbon that I already had rather than buying anything new. It gets covered anyway. But the major revelation came to me in one of those ah ha moments. If I am connecting the draping from the side seams I need a side zip, not a centre back zip. This required redrafting and reshaping the back. In doing so, I was able to take the excess ease out the of pattern and achieve a much better fit. The skirt muslin is now completed and tomorrow night we cut the silk. I'm terrified and excited!