It's not a terribly difficult exercise to setup with Turkey. We all agree Black is a must and probably Aegean and Eastern. Bulgaria is a given, and Greece wouldn't be bad to have. In fact, Ionian would be handy to start with, but not a must for survival. Only given A Bul, F BLA, EAS, and AEG, you could hold out for a little while as Turkey. If you have F Gre and F ION instead of F EAS, then you could probably hold out a little longer. Sevastopol would be handy to begin with, ensuring no Russian fleet exists (assuming F Rum is not extant), but again, quickly lost, no deal breaker.