While this does not answer your question, which I find interesting, it seems pretty sensible that you'd want to explore this option even if you are planting lots of trees. Doubly so if it's viable as a business venture, since that's a strong signal that it's cost effective.
As jsantos511 said many times, we need more shots on goal!
We see a lot of companies "planting trees " or "offsetting their carbon footprint" in their marketing material. However, they're not -actually- doing anything. They're just giving money to someone else that will "plant trees".
If I want to go ahead, and plant trees, there's no way for me, as an individual, to claim a bit of that money.
As jsantos511 said many times, we need more shots on goal!