I suspect UP might have words with them if the "heritage" SP scheme is too authentic...

I definitely do remember leaving from SF on the Suntan (my family wasn't going to drive to Oakland for that), and it was diesels of some kind (mid 1950s). It was a long train of mostly (Harriman at the time) commute cars with perhaps a Daylight-type food service car or 2. It moved along OK on the Peninsula and well south of SJ (Gilroy?), then slowed down a lot. Definitely stopped in SJ and at least once on the Peninsula (Palo Alto? Redwood City? Sleepy kid can't remember where even if I would have recognized it). The train stopped and unloaded everybody at the Boardwalk, then went away presumably to turn and park for the day - at the wye? None of us cared about that. It came back to the Boardwalk pointing the right way for departure around 4:00 and making plenty of noise so we would know it was time to board.