Thanks for the response. I watched some of Stanley Clarke's videos and re-read your post a few times but can't seem to find a way to really apply it properly. Once I get around the 14th-15th frets, my pinky finger just doesn't reach anymore. I end up pulling my thumb out from behind the neck and it just kind of sticks out, with my palm basically running against the bottom of the neck. Even then, I lose strength and accuracy in the pinky and the reach issue persists as I go further down. Are you actually putting your thumb on the other side of the neck, alongside the E string, instead of the G string?
Some of his videos are really interesting though.
Stanley Clarke upright bass solo.
I really like this. His playing is so organic. Its like nothing I ever see on electric. Remarkable bass face too.

I'm not entirely sure how to incorporate how he frets the higher notes onto electric. His hands are bigger than mine.
Stanley Clarke, "Schooldays" At Northsea Jazz Festival
I found this really interesting. Its because of the bass, actually. The neck is so thin, and it stays like that for its entire length. There's no significant widening before it joins the body. That must make playing up on the higher frets much easier. I don't have that option though.
Stanley Clarke Solo
He's using the same bass here as in that 2nd video. I notice that in both videos, his thumb goes over the neck when he plays. I think I read somewhere on these forums that some players do that to form chords that wouldn't be playable otherwise? But, I'm not at that stage yet.