How to do auto scaling for Rancher and Kubernetes clusters on AWS EC2?

Using AWS EC2 to install Rancher cluster. Then setup Kubernetes cluster from Rancher server.

About auto scaling, there are some ways to do:

There are many ways to do the auto scaling, but which is the best way? And the very important thing is, how to use AWS Auto Scaling for this architecture?

Or, is it good enough just use Rancher cattle environment to do webhook? At the same time, install k8s cluster from Catalog of cattle environment.