A somewhat casual proposal:
Because I like numbers...
Imagine
12

for solo
12 / n points for n-way draw
At the end of the game, you then subtract 4

from everyone
Anyone who is negative goes back to 0

and goes back to the bottom of the waiting list
I.e., in non-number terms
A win gets you next game and two Save-A-Life
A 2-way draw gets you next game and a half
A 3-way draw gets you next game
Anything less was an unsuccessful expedition by everyone.
What this doesn't capture is the scenario mentioned earlier where even in a 5-way draw, the top 3 get to move on based on SC count. It's probably my own known biases coming out, but I feel that's a bit silly. Either those 4th/5th people are essential to the draw / can threaten to throw the game, and should be rewarded, or they aren't essential but the other players must prove it. But that's my thoughts. I'm sure the method could be tweaked to allow more centre-based play if need-be.
I think it captures the arduous, never-ending climb of a mountain since 4

get subtracted every game (unlike something like the Leagues where you don't need to be consistent), and it not only punishes defeats but rewards solos. I doubt the two-way draw will matter but if you ever get two of them you get an extra life which isn't unreasonable for such a feat. And if you can't close out a game to three or less people, everyone falls.
Thoughts?