Just curious, if you are in Santa Barbara, why not grab a coach seat on the Coast Starlight just after lunch, have a nice ride up the coast, and spend the night in Emeryville? I know you'd get in at 9:30pm, so not much chance to sightsee, but the hotels are reasonable and you can still get a good nights sleep before the California Zephyr. A roomette in the CZ is a fantastic trip and I wouldn't want to stress out on a long overnight bus run that might not even make it on time. Bay Area morning traffic can be rough.
It sounds like a very creative itinerary, but Amtrak and the Amtrak busses aren't really known for punctuality. It doesn't just go boom boom boom. I've been riding Amtrak for over 50 years and have probably missed about 8 connections in all. If it is a guaranteed connection you'll get a free hotel room but you may not be able to get a roomette on the next days train, and you'd miss your arrival back East anyway.
Being a very long railroad, Amtrak has to deal with all sorts of delays, from freight trains blocking the track, temporary track washouts, your train or another hitting a car. That's happened to me countless times, always delays the train about 3-4 hours. Amtrak arrival times are really just suggestions on long trips.
You haven't said roughly when you were going to do this, but if you have any way to move the front end departure a day or even two earlier, you'll have a much better overall experience. If you *really* need to be back east on a certain day, you should probably fly and save the train ride for when you can relax and enjoy it, along with all the adventures that come along.
Hopefully I'm wrong, and please post trip reports here so we can enjoy "riding" along and help you with anything that comes up.
p.s. One of my best CZ trips was a complete accident. I was in Denver a few months ago, with a refundable air ticket to Boston. I happened for some reason to look up the price for a CZ/LSL roomette that evening, and it was dirt cheap, so I picked it up and told my spouse I'd be two days late coming home. It was because of a track washout in Utah, so the westbound train was stopped in Denver, sat for a day, and was ready to head back to Chicago completely empty. The train out of Emeryville was turned around at Reno. The eastbound passengers had to decide whether to take the free ride back to the Bay area or fly on from Reno to Chicago. Either way Amtrak didn't provide alternate transportation, just a refund.