While some of the portraits in my inspiration pile have a layer in between the linen camicia and the laced outer
|Photo from Wikipedia|
some clearly do not.
|From the Metropolitan Museum of Art|
While it's entirely possible that some sort of foundation garment was worn under the camicia, I have no idea what it might have looked like or how to construct it, so I'm going to go with just the camicia.
To me (and I'll be the first to admit I'm not an expert) it looks like these dresses aren't boned in the bodice. I have clothing with boned bodices, and there is always a shelf effect at the top. It's a result of the boning not following the curve of the body. All of the portraits I've found with this style of clothing lie flush against the skin.
What I'm going to attempt, therefore, is the same construction method used to make shaped doublets. In between the outer fabric and the lining I'm going to use wool felt and pad-stitch it to create gentle shaping over the bust. My theory is that the layered felt will be stiff enough to keep the bodice in shape while still molding to my body. It should also minimize wrinkles and buckling under my bosom.
Of course, I've never actually made a doublet in this manner. Before I start playing with the red silk, I've decided to make a practice version of the dress. It'll use the same construction method, but cheaper materials - in this case some cotton canvas, leftover wool from that cloak I butchered a while back, and cotton taken from an old skirt. That way I'll be able to make all the inevitable screw-ups and see how the dress wears in time to correct the problems in the "real" dress.