I towed my '06 19CCD for 4 years with a fully loaded Sprinter van that was also rated at 5000# tow and 500# tongue weight. Used an Equal-I-Zer hitch and never had a problem towing until I lost the turbo, alternator and transmission in a 5 day period 2 years ago right about this time of year. OUCH!!!! Was that ever expensive (out of warranty too!)
It was the van that was over-rated by Mercedes, but had no issues with the actual towing process at all. Just be sure that you get a good weight distribution hitch with anti-sway and you should be fine.