First question is where do you intend to attach said towing eye? My E39 BME has a tow eye that screws into a hole in the bumper after you pop a piece out of the bumper cover. A guy could make something like that and just remove one of the middle bumper bolts and replace it with the tow ring. Or buy one of the aluminum Tow ring hooks off Ebay that the Ricer and German car brigade use and come up with a bolt that works on the Shoebox. Or this has a 1-3/16 ID eye that should fit a tow strap hook and can be had with a 1/2 inch shank 1-1/3 inches long. A simple galvanized forged ring https://www.albanycountyfasteners.c...nized-shoulder-pattern-eye-bolts/1507-004.htm You can probably find something like that locally but make sure it fits the hook. https://www.albanycountyfasteners.c...nized-shoulder-pattern-eye-bolts/1507-004.htm
You can buy these, Racers bolt them to their vehicles [you can leave them hanging down in the breeze and you don't "Shin" yourself] On my Lotus Cortina, I used an Engine Lift Eye from a Mazda 323 and bolted it to the anti-roll-bar mount.
@Bo Lindberg I sewed up one of these from some excess webbing cut off a ratchet tie down. I used a "keeper" at each end which I can shackle together. Just leave one of these in the trunk , plus you can use it on multiple vehicles [simply wrap it around the cross-member]