For precedent see Lord Protector Cromwell.
I wonder if a post Washington as Protector USA would seek to turn the clock back to a collection of independent colonies / states...... I'm not convinced Britain would intervene (being quite busy with Napoleon at the time) but even if they did it's more likely to end up with pro-British and pro French factions in the states
No, I see the autocracy being the opposite: a more powerful central government in the form of the autocrat as a response to the US disintegrating under an Articles of Confederation-type government.
I'm still at a loss to how he manages to become dictator without every state saying, "Nah." For that matter, how Washington manages to hide his bid for political power throughout the war.
It would have to come after the war. The entire country is essentially in limbo until the war is over, because there's no trade, little money available, and the government's credit is worthless.