From your screenshot it looks like you could just resize the viewport. Ungroup everything, select the viewport and move the left edge over toward the model. Avoid double clicking on the viewport and avoid doing anything else that would make the viewport show as modified in the SketchUp Model inspector window.
Generally I prefer to size viewports so they fit reasonably tight to the model however in your example, it appears that your page border is on a layer higher in the list than the viewport so the viewport isn’t hiding anything. It really won’t matter if you leave the viewport as it is because your export will only cover the paper space anyhow.
I also normally leave the background turned off. You can do that by selecting the viewport and in the SketchUp Model inspector window go to the Styles tab. Untick Show Background.