Our trailer, bought used, came with a 2" hitch receiver welded to the frame below the rear bumper.
Although at first, I considered using it for bikes, for reasons that have already been expressed, I immediately removed it and hoped that it had not already caused damage to the trailer through use by the previous owner.
What has worked very well for me on our last three tow vehicles is to have a 2" hitch receiver mounted on the front of the tow vehicle and to use a standard hitch mounted bike rack up front.
Front mounted receivers are readily available thru hitch shops, but it may depend on what your tow vehicle is. I've had them on a Safari Minivan, a Sierra 1500
, and now a Sierra 2500HD.