Biome Creation - "Trees Per Chunk" option

Creating biomes with trees in it typically is an easy thing, there is a "Trees Per Chunk" option to allow you to define how thick or thin you want your trees in the selected biome.

But this value only bottoms out at 1 or 0..

What if you wanted less than 1 tree per chunk in the biome, but more than 0?

For example, the savannah biome has trees scarcely placed out with less than 1 tree per chunk. Certain other default biomes have this too.

I feel there should be an increase to detail on the number, allowing for decimal point values, such as 0.50, which would allow for a tree every 2 chunks or so, and so forth.

As it stands there "is" a work-around.. Adding a tree as a structure and introducing it into the biome that way allows for tree placement scarcer than this option would allow, but I find that conflicts with other buildings, causing terrain generation where a tree is poking straight through a building, or vice versa.