I have a wish-list item for NitroGen! I don't know if there is a better place to post this...
I don't know what exact options but perhaps something like this:
Main option:
Tree spread: Default / Random / Clustered
If selecting Clustered then the following options applies:
1. Size of clearing between clusters: Small, medium, large, Varied
2. Small clusters: None, one, few, some, many, lots
3. Medium clusters: None, one, few, some, many, lots
4. Large clusters: None, one, few, many, lots
5. Very large clusters: None, one, few, many, lots
6. Cluster Tree Density: None, Sparse, Dense, Thick, Varied
7. Tree density in space between clusters: None, sparse, dense, thick, varied