If it is possible, the time and money spent (aka, wasted) on trying to achieve this in PS using the above methods would, IMHO, be much better spent on having the photographer shoot a few more shots with different dresses with solid colors. With these in hand, one can easily change the (solid) color in a much more realistic and cost-effective way than any of the above PS-based methods.
There is an old saying that if one has a hammer in one's hand, everything, including screws, will look like nails. I think the request to use PS for this task is an excellent example of using a hammer for a task best done with another tool, photography, or photography plus some minor PS work.
OTOH, if I had a gun to my head, and there was absolutely no way to get a few more photos taken of the same model wearing a solid, so I had no choice but to use PS, I would find a good quality photo of a model with a similar build, lit similarly, but wearing a solid color dress. I would then copy the dress from this picture, and then warp, transform, liquify, and do whatever else was necessary to get it to lay well over the old photo and blend with it in an appropriate manner.
Even using this method, if your time (ie, in PS) to do this is costing someone $$$, my guess is that in the future whomever is paying for the work will probably consider more carefully the option of paying a photographer take a few more shots of the original model.
Tom M