Possible to render a route without unrendering previous route?

This might sound weird and buggy, so let me know if you have beter suggestions:

I am working on a route that basically displays a modal window. I know convention is to render the modal in a route action, but, I need the modal window to be bound to the URL so that if a user shares the URL (or refreshes the screen) they get to that view still. The experience I’m trying to mimic here is similar to looking at photos in facebook - if you click on a photo in your timeline, the photo opens in a modal window, but if you share that URL (or refresh the page) you still get to that photo (with no timeline behind it).

I tried overriding renderTemplate on my modal route and using its own outlet, but the default outlet is always un-rendered when navigating to this route. Is there anyway to prevent that from happening?