I've found the easiest way to survive the Crimean onslaught is to initiate it yourself. Ally Trebizond, get mil access in Circassia and georgia, then fabricate on Yedishkul. While your diplomat is working, ferry troops into Circassia. Once the claim is finished, then you can declare war for Yedishkul, and walk back and forth onto (and off of) Crimean lands. It'll keep their army in an eternal march (as long as you don't let them sit too long on your capital) if they do try to siege it, siege on of their provinces down (at this point you'll want mil access from Genoa) and walk across Genoese land to retake your capital. continue to do this until either the GH attacks or you can peace out for war reparations for the truce, Best part about this strategy is if you get lucky, you can keep Crimea at 0 allies until either the GH, Genoa, Circassia, or some other nation attacks, then pick up the pieces