The factory/OEM hitch has two additional securing points. Read more in
this post. I would try to get one of those (used would be fine I'd guess) if possible.
Some other considerations for towing:
Install an auxiliary transmission cooler in-line with the stock cooler. A B&M 70264 is rated at 24k GVW and will fit with no issues. See
this photo album for my mounting setup.
A Magnefine in-line transmission filter to help keep the fluid cleaner and prolong the fluid and transmission's life.
A complete transmission fluid exchange. Steps on performing one (as well as info about the Magnefine in-line filter) can be found in the general information thread linked in my signature.
Change differential(s) fluid using any synthetic 75W-90 gear oil. Also change transfer case fluid if applicable; any synthetic ATF will work well there.
Grease the driveshaft more often.