Development: Sarina's dress

I've gotten to the point where I'm happy with the basic design in 1/2 scale now, so I'm going to scale up the pattern and sew it in full size this week.  I'm trying it out on a greenish-grey silk first, as a sort of toile, before moving onto the nice expensive silk Sarina wants me to use for the final piece.  We're not certain exactly what we'll do with it though, as she only has two metres, and I've managed to design it with a masses of fabric in the skirt.  She has some grey/silver silk that we might be able to use with it, and make the tonal contrast a feature.
For the time being I'm going to sew up my toile, and then we'll have a better idea of how much fabric's going to be involved.  I had intended to use a crepe back satin for my toile at first, but Dexter was concerned that it was too heavy a fabric for all the fullness at the sides, and would make it look clumpy, so I've opted for the green-grey silk instead.
The other issue we'll have to look at when the toile is done are the open sides. At the moment, in 1/2 scale, they are open right down to the waist - which is a nice feature, but maybe not appropriate in a wedding dress.  I talked about possibly making/sourcing a matching slip to go underneath, and Sarina also suggested that a couple of little buttons either side might work too. But once again we'll wait until I've got the toile sewn up before we make a final decision on that.