Yes, it's very possible. With the hoe, stand in one place, and get everything as level as you can. in areas that are higher than normal, go whack them once or twice with the pickaxe, then go back to your "level" area and use the hoe to smooth it out. In areas lower than your level areas, use the hoe to raise the ground one, then smooth it out with normal how usage.

Rinse and repeat.

I've made some very large flat areas doing this.

There is also mods that can increase the hoe radius, I believe.