That said, the US was a sparsely-populated backwater outpost at the time with only about 7 million inhabitants (a million of whom were slaves). For comparison, the population of Europe during the same time was close to 140 million. We simply didn't have the manpower, infrastructure or money to meaningfully contribute to a European conflict at the time.
1 Napoleon wins in Europe does a deal with UK give me Europe and you can have the Americas oh and I want Lousiana back one of my cousins wants to be a king.
or
2 Napoleon stays true his ideals and backs slave rebellions in the south and caribbean
What reason would Napoleon have to attempt (and probably fail; the American navy was not nearly as much of a pushover as you state the army to have been) to launch a trans-Atlantic campaign against what was historically an ally and a strong cultural/political influence?