Any tips on navigating this complex process?

Nothing much is complex. Its pretty straight forward.

https://www.cbp.gov/travel/trusted-t...ntry/how-apply

Getting an interview appointment within a reasonable distance is very difficult, however. Even scheduling an appt. is problematic right now.

Unfortunately, that has pretty much always been the case for those of us in northern California. Not complicated, just bureaucracy. When I applied (years ago) there was a several months long waiting list at SFO, but much more availability at SoCal locations. So I flew SMF down to LAX, had my (literally) less than 4 minute interview in TBIT, had lunch and flew home.

You can get an interview at SMF but ONLY if you are arriving on one of the few international flights (from Mexico or I 'think' Vancouver).