I grew up around there. My #1 son was born in Mountain View. I am surprised La Honda Road is unchanged. Haven't ridden it in 30 years.
I know those silty trails around Mono Lake too. I knew you would get stuck when I read what you were attempting. In 2005 I rode my KTM 950 from Boston to Monterey for MotoGP. I spotted a similar track that appeared to lead to the Mono Lake shore. I got stuck a mile in. Not only that, but I couldn't put the side stand down or even get off the bike because of the tall duffels and all. Plus I was solo as my partners went on up the road to Hwy 395.
Well, I knew enough not to spin the tire deeper so I gently rocked the bike out using the clutch. Turning around was about as much fun, but I was able to get back to tar eventually.
I was told later in that part of the country the dirt all lava cinder or something like that. It's not really soil or sand. I agree, it is bottomless, whatever it is.
I have a hard time imagining you were stepping out the back end of that 500lb monster like a dirt bike, but hey...you're young and foolish. It took me years of dirtbiking around those parts to learn to slide a motorcycle and none of them weighed more than 250lb!
Looking for more updates. I am most interested in your take on the country once you begin your eastern path home. Hope you get a chance to ride parts of the CDR, but I think you'll need tracks for that. It's a good route for the big bikes.