What I've finally decided to go with, is a combination of the "Sanity as Skill Check" and "Classic OGL (CoC-style) Sanity" models. Sanity will still be tracked as a 1-100 value, but the actual sanity check will follow the d20 "roll over" model. The character sheet will have a "sanity table" to make these values easy to track, something like this:
I'm still looking at ways to integrate sanity with the SWSE condition track; I'm thinking that perhaps blowing a SAN check by more than your Sanity Threshold will move you down -1 step on the condition track. Losing more SAN than your Sanity Threshold, besides putting you in danger of temporary insanity, will also move you down -1 step on the condition track.
Thanks again for the help! Even suggestions that I ended up not using, were a big help in sorting out my thoughts.