It is plausible, you just need to get rid of the Central Rada, and replace it with Skoropadsky earlier, however you also need to add someone else who is not totally reviled by the Socialists so he won't need to go to White Russians to get bureaucrats and officers.
I think Vasyl von Hapsburg is by far your best bet in this case. I have often pondered this same scenario.
Here is how I imagine the basic TL. [X]=under consideration
1917
- Skoropadsky forces the Rada to declare an independent Ukrainian state with Vasyl as King/Hetman
- Skoropadsky and Vasyl try to organize the Armed Forces, includes as OTL Black sea fleet, aswell as the ~300,000 troops who swore allegiance to the Rada before being dismissed by the Socialists in the Central Rada
1918
- OTL Skoropadsky managed to form a functioning gov't in his short time in office, ITTL with even more time, he and Vasyl organize a stronger military ~300,000 strong, plus the Black Sea fleet
- [Soviet's invade as OTL, get beaten badly by much larger Ukrainian forces. Bolshevik uprisings are crushed.]
- [Ukraine and the Soviets sign peace]
- King Vasyl and "Marshal" Skoropadsky send a few divisions to the Kuban peninsula joining with the Kuban People's Republic
- The Central Powers collapse as OTL
- Polish forces quickly take over L'viv (IOTL Ukrainian units that would ITTL be in Ukraine were in L'viv and managed to capture the city early on)
- Ukraine declares war on Poland
- Ukrainians forces move to surround L'viv
1919
- Ukrainians manage to take L'viv, in Chortikiv' offensive*, led by General Hrekov (named so due to HQ of Ukrainian Army being based in the town of Chortkiv')
- Rumania seizes Besserabia and Bukovnya
1920
- Ukraine and Poland are still fighting when the Soviet Union launches an offensive into Ukraine and Belarus
- King Vasyl personally commands defense of Kyiv manages to stop Soviet offensive
- [Ukraine fights a war on two fronts until the League of Nations pressures Ukraine and Poland to sign a ceasefire to fight the Bolsheviks]
- Ukraine and Poland launch offensive in Belarus, Ukrainians take Minsk reestablishes Belorussian People's Republic [Or annexes south Belarus' and partitions Belarus with Lithuania]
1921
- Ukrainian Polish ceasefire breaks down, Ukraine signs peace with Soviet Union after taking Kursk surrounding Orel** (remember Ukraine's much larger ITTL military and German-Austrian aid)
- Ukrainian Polish War resumes, Poles launch offensive in Belarus and Galicia. Poles almost retake L'viv, Ukrainians launch counter offensive in Volyn' threaten to cut off Poles in Belarus'
- White Army forces are on the run
- Ukrainian forces push the Poles back from L'viv
- LoN moderates peace, Ukraine keeps L'viv while Poland remains with Peremyshyl
*IOTL Ukraine almsot managed to take L'viv outnumbered 5-1 running low on supplies, artillery, and guns, when they actually outnumber or at least have numerical parity with the Poles than Victory is assured.
**Neither city is annexed into Ukraine, however the fall of such important Southern russian cities would panic Bolshevik leadership, as the whites are still going strong.
This is an old rough timeline of possible events I've had for a long time. I one day want to make it into a TL, though I've been too busy working on a current project. This, rough outline could certainly use some work.