Create a custom editor window with repeating subsection (mockup included)

I'm making a game that uses a variety of self-learning units. There are tons of parameters to tweak which produce different behaviours. I want to make a custom editor window that allows me to easily adjust the number of units being trained and easily look at the parameters of each.

Here's what I currently have. This is just created using EditorGUILayout. Note that this would only allow me to spawn and adjust one unit.

What I want is for the above to behave a little like an array does in the inspector, i.e. a "size" box which creates a number of identical but unique boxes like the above, which I can then scroll through. Here's a mockup:

Maybe I could achieve this by making a simple serializable class for storing all the data and then just have an array of instances of that class? But then how would I make it show up in the window with the correct layout?

Thanks.