I've got a wordpress based site which utilizes a complete page caching system. Issue is that I have to add dynamic content for drenched in customers. At this time I am keeping the caching enabled for non-drenched customers and disabled for that drenched ones via cookie check.

Would placing the dynamic content within an iframe be a suitable means to fix extend the entire page caching to any or all the customers? Or much better ways?

Another approach is always to pull within the dynamic contents via AJAX. Obviously your page won't be accessible without Javascript, but that might be an problem.