Chunk loading!

Hey so I’ve dug out a massive 9 chunk x 9 chunk area under where my base will go and I’ve put all my farms down there I’m wondering how do I load all the chunks so all my farms stay running, I want to use portal loaders but I can’t seem to think how that would work as the portals would be to close nether sided, I remember seeing a tangotek video of how he will have all of DO3 loaded but can’t seem to find it any help appreciated. Thank you!