My attempt at this bounty.
Comments
To have her wear her mask, remove tags relating to her eyes, face paint, etc., and try adding "mask on face" or "mask" to the positive prompt. Prompting it can be a bit tricky as the dataset contained ~6 examples of her wearing the mask on her face. The training set did include an additional 6 photos of cosplay masks.
Every image was manually labeled. (Invalid tags were used in training for Pony V6 XL and Animagine XL V3.1.)
The model was not trained on explicit material.
Most of the training data contains her core outfit, and may sometimes require a bit of tinkering to change to a novel outfit.
Images
Common training sizes: 1280x704 (x16), 1344x768 (x13), 832x1152 (x10)
Signatures were removed from fan art for training.
x114 images of San
x32 screenshots (x2 repeats)
x62 fan art
x14 cosplay
x4 pvc statue
x2 yarn/cloth doll
x6 photos of isolated cosplay masks