It wouldn't be hard really, have the British side with the American settlers and no more Quebec Act, it was a serious bone with the British Americans, which fulled the bucket for the revolution to boil over. Some saw it as a disgrace to the faith at the time, if only they knew it would lead to they're independence.
A few years of difficult rule, and attempts to set them to the British system, with encroaching Anglo settlement. There'd be religious tensions too, as every Anglophile would be Anglican. Even the French settling would be Protestant, the... shoot the name escapes me at the moment, I'll edit when I remember. It was a deal between the French and the English to trade each others religious counterparts. As in English Catholics for French Protestants, and use them for settlers. That's why theres a lot of Leblancs in New England, and such. But those would be the Horse kicking the lantern, in unison.
You might not see a USA, not at least how you might think. Le Québec Libre, would drive the Americans closer to Britain mainly for support. The American colonies, heavily out populated the Canadas. They just need the Fleets the RN had. Shoot this might lead to an American focused British Empire.
This one caught my eye right away, and you're right there's not enough Quebec on here. Serious Quebec, not the yes/no vote, guns a blazen stuff. If Quebec had the chance to make it alone, it would have been either just before the Plains of Abraham, make a claim as the British were dismantling the French, New World Empire. Siding with the Brits offering to take their Catholics, and opening its ports and trade centres, approach.
Or in the 60's with the quiet revolution up to the 80's but not after the crash, as it accounted for 1/3 of Canada's economy, and then Alberta awoke. Anytimes in between, is dicey at best, they were stuck in an outdated agrarian economy, until after ww2 or having to work with the rest of Canada, in war or hard times. Plus, Laurier, that guy had something about him that made it work baby. Until he started that prattle about reciprocity and free trade with the USA.
Pardon the rant. I don't post much, you can see why. I like the idea though, ride it... just don't let the Maritimes become states please? I'd be down with a semi independent duchy of Nova Scotia, with ties to the crown. Even a more versed, version of government that came about in 1848. Just don't let them become part of the US, they never wanted to, they only wanted to trade with them... ha... haha. Good Luck with this!