Here's the list of models whose work is entirely or mostly SD:
Sama
Danielle
Beverly
Jynx
Mariah
Madison
Rachael (Ten Amorette)
Autumn Bodell
Lavender
Angelique
Audrey
Melanie
Christina
Lily (70% of her movies are SD)
Amber Wells (about 50% of hers are SD)
All suggestions welcome.