First, a shackle (D-ring) is a closed recovery point so there is no chance a tow strap inserted into it could pop out. And there is far less of a chance any other type of recovery cable, etc. would pop out of a closed shackle when compared to an open hook. They are preferrable to an open hook.
So far as the antenna mount goes, I am a 2-way radio guy and except for the 102" whip antennas which I never recommend for trail use, I never recommend bumper antenna mounts. Bumper mounted antennas have to be extra tall, like 5' or so, to clear the tub and the fact that such a high percentage of their overall length is next to the steel tub which detunes them is not a good thing.
I prefer a higher mounting location, like on top of the spare tire bracket as seen below, or perhaps a tail light mount like you can find on TeraFlex • Jeep Suspensions, Body Protection, Low Range Gearing and HD Axles
. A 2' or 3' antenna mounted at that height avoids being next to the tub and it will just work better than a longer antenna mounted onto the bumper.
The first pic shows how I used to have my antenna mounted behind the spare tire and it worked very well there. I only moved it after I got rid of the factory spare tire mount.
The second mount is about where the Tera tail light mount would place it, and Tera makes a version for both the driver's and passenger's side tail lights. Just make sure if you go with Tera's mount to grind away the powder coating and paint between the mount and tub so the mount is adequately grounded. And grind a little ring of powder coating away from underneath Tera's mount where the antenna mount's lock washer and nut are so that part of the mount is grounded too. Leave the top of the mount alone, it needs the powder coating on top.
The one in the second pic below isn't a Tera mount, I welded a tab onto my spare tire carrier bracket for mine. I just showed it because that's a good location for a CB antenna.