Also if your are able to use apache on a port besides 80 you don’t need a reverse proxy. Which is what I am doing. You can also search the topics by clicking the search button located at the top right of this page and by typing in “reverse proxy” without the quotes you may find your answer without looking elsewhere.
Not sure if you're still looking for a writeup answer for this one, but I ran into this same issue and solved it using http redirects as suggested. Apache is still running on port 80/443 but uses redirects to forward requests for trailer.apple.com to the plexconnect server listening on ports 9999 and 8443. Full step by step writeup is over on my blog. http://www.linuxtoolbox.ninja/?p=60