suggestions on how to repair cracked 2012 Prius rear bumper cover so it passes MA state inspection?

I used colored duck tape

 

You can find aftermarket ones on ebay for about $150

 

The cheapest long-term fix is to drill holes on either side of the tear, and then use black nylon zip-ties to stitch it back together.

For best results, remove the bumper cover and do this while it is off the car, then reinstall it. Use black zip-ties because they are UV-proof, all the others will degrade and break down in sunlight.

Random example found on the internet:



If you want to get really fancy, do it so the pawl end is on the inside of the bumper- gives a cleaner finish.