If it’s just textures and the landscape, you could get away with using the landscape system or just a dynamic mesh and Runtime PCG instead of voxels. I generally use voxels for being able to “dig” into terrain or build it up in shapes that 2D landscape data couldn’t do.
It sounds like those fields could honestly just be bounds set up to determine where the PCG elements are supposed to generate, and doing any of the actions (Tractor, Harvester, Planter, etc) in that area would just paint (using render textures possibly) the textures to the landscape, call for PCG generation of elements there, then handle the field itself and it’s characteristics as data.