Here is a link to the Superhitch. Yes it is in the $500 price range, probably even more because you need to replace the hitch then buy the extension for $500.
http://www.torklift.com/products/supertruss.phpBut it is strong!! No worries about towing a mere 5,000 pounds, or even some horses in a 9,000 pound trailer!

I can understand your budget though. You can buy a 24" extension, combined with a normal or perhaps longer hitch receiver, will get you most of the way from being under your camper. As long as there is about 8" from the top of your hitch to the camper, you should be fine. But also you will need to be able to back up and get the trailer about 45 degrees from the side of the camper (as in a sharp turn) and not have the front of the trailer contact the camper (that would be a bummer).
ETrailer.com probably has a 24" long extension, and also might retail the Torklift for a better price than other retailers. Look for a Reese extension, or call the 800 number, and let them look it up. they do sell items that are not on the website.
the nice thing about Torklift is your turnbuckels will bolt right onto the new dual receiver hitch in the back.
Fred.