First, to share what I've been doing:
This has worked moderately well, but it does require quite a bit of effort and fine tuning. Also, the fact that I am just using two fishing lines diametrically opposed means that lateral movement is completely halted, but there is still a bit of give in regards to moving forwards and backwards. If the doll isn't well-balanced at this point and does move along one of the non-reinforced vectors, the whole thing could end up collapsing (hasn't happened yet, but I have been pretty careful and have abandoned several poses when I felt like things weren't going to work out).
I have been thinking about getting a low profile stunt harness at some point, but that obviously would not work well in this case where she isn't wearing all that much. And, obviously, I could just lean her against some furniture or a wall, but, at the moment, I'm focused on full body model shots in the middle of a studio where it's just the model and nothing else. In the future, especially if I do location shots, I can easily use the environment to help support her, but we're out in space here! Oh, lastly, this would be easily solved with an assistant, but I don't have one (yet).
So, photographers and engineers of TDF, what do you do to make your dolls stand on their own two feet (or one (or hell....none!))?