Custom ecs-optimized Amazon Linux 2 for Batch

Following https://docs.aws.amazon.com/batch/latest/userguide/create-batch-ami.html, it says to stop the Amazon ECS container agent w/ "sudo stop ecs". That throws an error, i assume you meant "sudo systemctl stop ecs"?

I need the image to do some setup before it starts accepting containers. I understand that User Data is suggested for this (https://docs.aws.amazon.com/AmazonECS/latest/developerguide/example_user_data_scripts.html). However i found creating a custom systemd service and installing/enabling it before creating the custom AMI is a much cleaner solution. I haven't found much documentation on creating custom systemd on ecs-optimized Amazon Linux 2. The created image does correctly run the custom systemd service. Is there any potential problems with this approach instead of using User Data?