You don't need an extension to do this. Set up your SketchUp template with the scenes already named. Make a simple model in that template to use as a proxy SketchUp model you insert into your LayOut template with the viewports arranged on the sheets as you want. When you start a new project in SketchUp use the template with the scenes you created. You can change the camera position and other scene properties to suit the new model but leave the scene names as they are in your template. Then when you're ready for LayOut, open the LO template and in Document Setup>References, relink the SketchUp reference to your project file. The viewports will all update to show the scenes from your project model.

FWIW, an extension won't make the viewports display the model any faster. LayOut will still have to render them. Likely there are things you can do in your SketchUp file to optiize it so the rendering time is reduced. I'm going to also guess you could manage with fewer scenes in the model if you wanted to.