Thanks again for the info.

I was speaking to a mechanic who installs trailer hitches, and he said that the concern with the G37 is that the structural part of the bumper is not made of steel, but of aluminum which can fatigue. Do you think this is a concern?

 

I did some further research, and both Curt and U-haul recommend using a stabilizer strap on hitch mounted bike racks on most Class I and II hitches. Curt even sells one: Bike Rack Support Strap part #18050. U-haul also sells it under the same part number, probably the same item.

Here is a link to the item on Curt's website.
Here is a link to the item on Amazon
Here is a link to the item on etrailer.com with videos

 

Don't know if this would be an option to consider but SeaSucker has a nice setup using suction cups.

 

The Sea Sucker is a nicely designed option that's quick and dirty, but there's the potential to scratch your paint at the suction cups. It's also easy to forget you have a bike on your roof, which is why I like the hitch mount. If you are using a good, properly installed hitch mount, like the Curt, spend the extra money for a good tray type bike rack. There will be absolutely no need for that goofy stabilizer strap with a rack from oneupusa, thule, or if you want the best, kuat.