Sig,
A client of my company is Armorshield LLC which is a wholly owned subsdiary of US Cavalry.
They provide just such a product called the 'Couger' under their 'Covert Armor' line. It supports add-on drop-in ceramic plates for high velocity and rifle round protection as well. All designed for undercover concealed under clothing coverage.
COUGAR™
I have not directly seen this product under go testing nor have I worn it yet so I cannot speak to it's capabilities or comfort as by intent of application.
- Janq