1bigtracker: I thought about using zip ties, but didn't like the idea of having to break them every time I wanted to use the rings, having to carry spares to replace them after use, etc... The magnets are much simpler and work great.
jagular7: sounds messy and not very esthetically pleasing, if you know what I mean. The magnets are virtually invisible while in use and instantly removable, and can be stored right on the bumper while I use the rings.
safarikick: I thought about routing my winch cable through them like that as well, but didn't want a kink or bend in my cable and like the rings to stay nice and flat against the bumper when not in use.
Wild, you're welcome for the tip!;D

As for not having a winch, look into the one I have. it's a Milemarker E3000 and I got it from Rough Country/Heckthorn for $181 + $10 shipping. Then I added a quad roller fairlead from Ebay for $15. Even single-line pull, off center by about 45 degrees it was strong enough to drag my Tracker up/over a large boulder and tree stump without even getting warm!