I suggest making the corset and adding two thin clear plastic straps near the bottom of the lightning slit to keep it closed.
PVC is also quite unforgiving with the holes the needle creates. You have to be sure of where you are about to stitch. I think pleather would be a little easier to hide mistakes in.
Trish is quite blonde by the way. One of the trickier bits about her is her hairline... it's hard to do with a wig and make it look nice.
Do the job, till it's done Sir