Hi Ed,
Here are two method I recommend is
1. Use Iframe with dynamic content to deliver, highly personalized content based on customer profile data.
2. Use Rest/bulk API to query data about customer from Eloqua and deliver ADC content via REST.
You can debate which is better but I have used both, depending upon traffic and many other parameters, for Opencart, Hybris and Magento.
Hope this gives you few options to consider.
Thank you
Amit Pandya