The CSA should have hired him to print their currency for them, no one would have had to know.
I once ran across an article saying that the US Treasury was involved in counterfeiting Confederate currency. I couldn’t find it this time but this other article was equally interesting.
The Secret Service was created by Lincoln and its sole job was combatting counterfeit currency. Ironic. In the 1860s and up until 1913 banks printed their own currency, and the multiplicity of currencies created a rich environment for counterfeiting. Estimates of the amount of fake bills at the time are amazing. Something like 30-50% IIRC.