A stackable system while living sustainably is taking into account which systems will work better together than apart, and going with the flow of that.
For example if you plan on having an organic garden consider also having chickens. Why? They stack.
Gardens get insect pests and a natural predator of bugs is of course poultry. Chickens on the other hand need a certain amount of protein in their diet along side the grains we feed them. It is a good idea to fence off a small section of your garden every day for the natural inclination of the birds to go foraging. This keeps them safe, gives them what they need and in turn helps you control the insect population munching on your prized pumpkin patch, and that is a beautiful thing.