The problem is that the natives just don't have enough population to keep American settlers out. The only way any 'native' polity could survive is under British protection - and the Brits are far more concerned with trade with the US than their own colonies, like Canada, let alone any native protectorate.
Your best bet that has any plausibility is a much better British/Canadian effort in the War of 1812 (which really needs a PoD earlier to, at minimum, get the French speakers interested in the war effort), and even that will give you only a territory with a native minority (at least a couple of generations later) with some constitutional protections for native rights.