After finding the UK trainers and jockeys portraits mod, I decided to create my own for the U.S. trainers. If ya'll like it I will upload the U.S. jockeys as well.

Instructions:
Unzip file and copy/paste all files into:
gfx > portraits > 2 > trainers

Do NOT alter the file names or else they will not load in the game.

You can download it here.