Is it possible to configure a global redirect for port 80 to 443?

 I don't think this is something that can be achieve without a Virtual Server as Virtual Server is something which is termination point for the application which acts according to the configuration done on it.

One thing you can do is instead of creating two different Virtual Servers, you can achieve both use cases, redirection from 80to443 and handling actual application traffic using single Virtual Server. No need to create separate Virtual Server for only redirection from 80-to-443.

For this, you need to have one virtual server which will be listening on both port 80 as well as 443. So when traffic is coming for port 80, redirection will happen and if it is coming for 443, that will be actual application traffic.

This can be achieve using iRule and also using shared object of type port lists. You can create shared object with two ports and map it to the Virtual Server. You need to check if your current F5 version supports shared object. I think it was introduced in v14.

Also you can even have multiple applications behind one Virtual Server with the help of iRule so you don't need to configure separate Virtual Server for each application.

Hope it helps!

Mayur