The good thing is that Goodyear will pickup the total bill if you hold their hand to the fire. They must get the failed tire back via dealer.
It appears that you have a 2011 Montana 3580rl. That would have 7K axles derated to 6750 pounds so they could they could install those Marathon's rated to 3420 each, allowing full 90 pounds of excess capacity per axle.
You could lobby for GY G614 tires, however your wheels most likely are not rated for the 110 pound inflation tires.
So Keystone put you between a rock and a hard spot just like so many others. Be sure to file a report!
https://www-odi.nhtsa.dot.gov/ivoq/Chris