Your challenge is simple-have Russian North America be larger than OTL. In particular, have Russia expand into, and settle, OTL British Columbia and the Pacific Northwest. It shouldn't be as hard as it sounds-if Russia gets as far south as I specified, they'll have the Frasier, Willamette, and Columbia river valleys, all of which contain productive agricultural land far more ameanable to European farming techniques than Alaska is. Also something to consider is that both the French-Canadian and Afrikaner ethnic groups weren't descended from that many people-only 1,000-2,000 or so. If we get the Russians to bring that many people to the Pacific Northwest in the 1700's, their won't be any major settlement of the region by anyone else until the 1840's at least. Even if Russia ultimately looses the area, the impact of the Russian language/culture on it would probably be considerable.
Thoughts?