The following guide is great for machines that are on premise, But remote users are not affected by it. 

https://www.manageengine.com/products/desktop-central/agent_installation_windows_gpo.html

The only solution I see is running the startup script as an immediate scheduled task. To ensure this script is executed on group policy update.
https://4sysops.com/archives/run-powershell-scripts-as-immediate-scheduled-tasks-with-group-policy/

Can anyone offer any guide to run the startup script as a scheduled task?

Thank you