AWS EC2 Instance - Without SysPrep

Not sure if this is the kind of solution you are looking for, but see if this helps. SSM Automation is a service that allows customers to configure, deploy and manage their AWS resources at scale, in an automated way by defining runbooks. A runbook is a sequence of tasks that the service performs on behalf of the customers. One of the actions supported by the service is aws:changeInstanceState which allows you to change the state of EC2 instance(s). More info can be found here - https://docs.aws.amazon.com/systems-manager/latest/userguide/automation-action-changestate.html