[quote=@Mihndar]
<Snipped quote by Vilageidiotx>
[/quote]

[url=https://en.wikipedia.org/wiki/Ukrainian_State]It does have historical, and by virtue of its use, a linguistic basis. 
[/url] Calling it the Kingdom of the Ukraine gives off an amateur NRP vibe since they've typically used the term Hetman in place of monarchical titles. Since you are creating a monarchy out of thin air, you're going to grab for the nearest comparable tradition, and the Cossacks got it.

Best way to play it is just call it "The Ukraine" with its leader titled as "Hetman"