Was the title Fear and loathing in las vegas a subtle homage to George Orwell's Down and out in paris and...?

You know that he was familiar with the work and admired it. So the phrase and its rhythm would have been bouncing around in his head, which suggests at least a subconscious echoing. More than that, can't say without research and I see you've already made a start. Sounds like a needle/haystack kind of thing and I'd rather be reading Orwell. :-)