You have taken all the actual issues that come with "Closed" into account I hope. The only campground open will be Mammoth. There will be no water, no showers, no dump station. The commercial RV parks in Gardiner will also be closed, so no water, no dump. Maybe you could get those services in Livingston, which is 55 miles away, but maybe not. Dunraven Pass will be closed, so will the Beartooth highway. Snow will likely close other roads intermittently. If there is significant snow, the park service does not respond to clear the roads like Denver does to clear the interstates. They will be on a skeleton crew and the road may stay snow-packed for many hours. Lots of risk to take on a long expensive journey away from home. And this year COVID may restrict you even further. Wouldn't be out of the question for the park to completely close September 30 or even if case rise. And when I say completely close, I mean shut down the gates and you cannot get in. Something more to consider.