I can't exactly answer your question, but I strongly encourage you to donate your organs. You can easily save 3 or more lives.

My plan is to do that, and have my remains naturally buried. But natural burial grounds vary by state (if you are in the US). Some states allow natural burial on private property, with some caveats (acreage, ground water).

It's kinda complicated and requires you to look into your state/county laws and nearby natural burial grounds.

I personally hate the idea of pumping our bodies full of preservatives and sealing it in a concrete tomb underground. I also hate cremation, even if it is accompanied by planting trees over the ashes.

I think the best legacy is to transfer our ATP to organisms in a food web. How cool is it to imagine our energy transfered into fertilizing plants and eaten by insects, which are eaten by frogs, which are eaten by snakes, and then hawks, etc.

So much cooler than wasting it in cremation or trying to preserve a useless empty vessel. What cooler legacy is there than allowing your energy to be carried on through an endless chain of diverse lifeforms?