I actually had my flights structured as such:

SAN-LAX (last flight of day)
LAX-SMF (first flight of next day
Total: $119

Counts as a through connection, but agent warned me, "If you oversleep, or don't make that flight for any reason, your credit card will be charged the full SAN-SMF Y fare of $250!"

Anyway, here's how the story ends with me. Instead of playing this risky game that violates rules, I had them attatch my SAN-LAX leg to a future one way LAX-YVR leg (which cost $300). The SAN-LAX flight added $150 to the onward travel, even though the YVR trip is a few weeks away.

Then I thought, "hmmm, I wonder how many more legs I can attatch." I was able to also get PHX-LAX-SAN onto the YVR ticket at no extra cost!