Hunter S. Thompson wrote about this when reflecting on Fear & Loathing in Las Vegas. I found it labeled as "previously unpublished" in the Gonzo Papers vol 1.

Which gets down to a final point about Fear & Loathing in Las Vegas. I have called it, only half sarcastically, "a vile epitaph for the Drug Culture of the Sixties," and I think it is. This whole twisted saga is a sort of Atavistic Endeavor, a dream-trip into the past--however recent--that was only half sucessful. I think we both understood, all along, that we were running a hell of a risk by laying a sixties trip on Las Vegas in 1971 . . . and that neither one of us would ever pass this way again.

[...] Because it was nice to be loose and crazy with a good credit card in a time when it was possible to run totally wild in Las Vegas and then get paid for writing a book about it . . . and it occurs to me that I probably just made it, just under the wire and the deadline. Nobody will dare admit this kind of behavior in print if Nixon wins again in `72.

The Swine are gearing down for a serious workout this time around. Four more years of Nixon means four more years of John Mitchell--and four more years of John Mitchell means another decade or more of bureaucratic fasicsm that will be so entrenched, by 1976, that nobody will feel up to fighting it. We will feel too old by then, too beaten, and by then even the Myth of the Road will be dead--if only for lack of exercise. There will not be any wild-eyed, dope-sucking anarchists driving around the country in fireapple red convertibles if Nixon wins again in `72.

[...] So much, then, for The Road--and for the last possibilities of running amok in Las Vegas & living to tell the tale.