1) AFAIK Russia's hold on the far east was not that complete yet, it was still largely uncontrolled.
2) around astrakhan, the Kalmyk Khanate should still exist (are you using VIP? if so, then Gelugpa, otherwise Mahayana)
as in that map, maybe Russia gets astrakhan but the adjacent provinces go to Kalmykia.
also, have you considered waiting until OHgamer finishes with the Clio map and using that? it would be a good way to showcase your mod. however it won't be out for a while, so maybe that isn't such a good idea.