Well, the other option would be to get a rear bumper with a 2" receiver. You can use those as a tow point.
The only problem I see with those stype of shackles is that they only use the crossmember as an attachment point, which can bend. Same goes for bumpers though too. If I was going to get pulled by the rear like that I'd loop the strap through both links so it pulls evenly. Although most of the time you're not really that stuck and I doubt you'll get that stuck with your setup.
In any case you you can use them. Cut them down and use them on your bumper later...