Looks like google does support this with analytics.js now, it just needs a line of javascript added:
https://support.google.com/analytics/answer/2444872?hl=en&ref_topic=2611283
To implement Display Advertising features for Universal Analytics, insert the bold line into your existing tracking code between the ‘create’ and ‘send’ commands, as seen in this example:
<script>
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,'script','//www.google-analytics.com/analytics.js','ga');
ga('create', 'UA-XXXXXX-XX', 'example.com');
ga('require', 'displayfeatures');
ga('send', 'pageview');
</script>
Given the location it needs to go, this doesn’t look like something we can easily do with the current settings.