Adding custom parameters to Facebook pixel within extension

Question

We're using the Facebook Ads Extension, which is great for feed creation but I can't see a way to edit the pixel so I can add extra parameters. I actually want to add;

fbq('track', 'PageView', {
referrer: document.referrer
});

instead of just;

fbq('track', 'PageView');

In GTM I could add the base code again with this included but that would fire the pixel twice. Is there any way to customise the pixel in the Facebook Ads Extension?

Thanks

Richard