I say get the right shade of tuquoise bra -- Victoria's secret always has those kinds of colors -- try it on and see if it looks to bra-like and then go from there in terms of possibly covering the straps or something. I'm inclined to think you might be fine with just the bra. In this photo, I have a regular bra underneath the mesh. It's actually not the best bra for the job because it has a lacy band and that shows. But I think if I find a solid turquoise bra it will look o.k.
I agree that the dress needs a slit. I would think a slit to the knee through the mesh panel would work, edge finished with some light weight beads maybe.
Sedonia
