There are a few bumpers out there rated for towing, I've seen a couple, but I don't remember where I found them. (I spent months browsing the web before I picked out a set of bumpers, lol)
Some of the ones that are NOT rated, are still good enough for towing, just not rated (liability issues, as Schnutzy mentioned).
I bought
Dirtworx, they're not rated for towing, but I heard from a few people that use these bumpers to tow with.
Also, use frame tie-ins.
Welcome to the Forum:wavey: