Can I use packer to build my big windows container images or not?

Your docs are unclear to me:

At the top of the doc it says:

Please note: Packer does not yet have support for Windows containers.

But then on that same page it says:

Docker For Windows
You should be able to run docker builds against both linux and Windows containers…

This is what I would hope to achieve with packer:
I have huge (20gig) windows containers. Building and running these locally is almost impossible. So, I stand up an EC2 instance with docker on it, remote into it, build, run, poke, push it from there. This is a pain for me to do manually.

Can I use packer to automate this? So packer would provision a windows EC2 instance with docker on it, build the container, maybe run tests to validate it, then push to ECR?