A custom image with a simple cronjob in the instance that shuts down after preset minutes of up time. This is not ideal way, but get things done.
We have already tried the demo server, but for many instances its not suitable with the setup.
I came across this post with your reply and seems snapshot expiry approach could be replicated for this use case as well. There seems to be already a script available that can handle expiry string.
Colleague has created an issue.