Optimizing Mixpanel for Accurate Page View Tracking in SPAs

hi- all pages in our web app requires users to log-in. when user clicks on any of those page, they need to sign-up/log-in to access the page. I have mixpanel client SDK implemented via Google Tag Manager and capturing Page View event. I noticed that Mixpanel will capture a PageView URL when user lands on the page before the signup/log-in, and another for the same page after user completes sign-up. This makes analysis difficult as we see page view event for many users who just never register or signup. How can I setup mixpanel to record page view when page content is full visible. Our webapp is single page application.