To the east of the River Dnieper, they would center their pro-Russian state around Kharkhiv.
Crimea already has its own parliament and a large measure of autonomy.
I believe Ukraine corresponds roughly in size to Texas (but I could have that wrong. Perhaps it is bigger. I'm guessing.)
If memory serves it was called the breadbasket of Europe (the soil is as rich as the great plains), before the communists took over and they ended up with 70 years of bad weather.