A node in the fedorainfracloud would also work

Great. I have created:

fedimg-dev.fedorainfracloud.org

It should have your ssh key from fas on it and you should be able to ssh in as root. I made it a rhel7 instance since thats what our fedimg instances are, but if you need/prefer something else, just let us know.

There's also a playbook for it in ansible in playbooks/hosts/fedimg-dev.fedorainfracloud.org

You're welcome to use that to configure it, or just do it manually as it's a dev instance. If you need perms to run the ansible-playbook, just let us know.