So I did the trip myself, and had to find a way to do the shuttle using public transit.
I drove down to San Quintin and rented a room at the Old Mill Restaurant/Hotel right on the water at San Quintin Bay. I packed my kayak in the room to make sure I had everything out of the truck. I left the kayak on the bed in the room and at 3:00 PM I started south to Guerro Negro. There was lots of construction on the road and it was a long drive. I didn't arrive until after dark at 9:30 PM. I left the truck parked in the courtyard of the Hotel La Posada de Don Vicente and ran off to try to find the bus station. A friendly woman on the street named Lupita gave me directions which took me directly there! (There is a strange connection between the name Lupita and kayaking in Mexico).
Baja has a very nice bus system that runs up and down Highway 1, the trans peninsular highway. Brand new modern busses, air conditioned, cushy seats, video screens showing movies (in Spanish, of course). But you cannot get any information about it in advance. There is no schedule posted on the internet. There is no phone number to call for information (even if you spoke good Spanish). You just have to show up and hope a bus is leaving soon. This is very stressful for someone driving 1500 miles and abandoning his equipment one piece at a time along the way, hoping to get back to everything. Every year I search the Internet for information about this bus system and usually turn up nothing. This year a travel guide book had a page about it with an information phone number! I called it and asked if someone could help me in English. The woman on the other end tentatively said yes. I asked her about the bus schedule and she interrupted me to say “The Internet is wrong, this number is not for the bus, it is a private house!” Oh No! I wonder how many calls she gets every day!
Finally at the bus station in Guerrero Negro, I asked about a ride in my poor Spanish. With with the help of someone behind the counter who spoke a little English (much better than my spanish), I learned that a bus was leaving within the hour and my troubles were over! I turned around and beheld an apparition mounted on the wall behind me: A professionally printed sign with all the bus times on it. I'm publishing a cleaned up version of this sign here as and aid to all Baja travelers. Do all the bus stations have wonderful signs like this? (No. On my trip back north I found no sign in the San Quintin bus station and a hand written sign in El Rosario that required 10 minutes of rapid-fire Spanish to explain. None of which I understood, but I thanked the bus station attendant anyway). No matter, the sign at Guerrero Negro is in the middle of the peninsula, and you can use it to predict when the busses will leave all the rest of the stations north and south. This is the Rosetta Stone that should make it possible for future travelers to use this wonderful bus system more often. Of course, the bus is often late and this day was no exception. The bus finally picked me up around Midnight for a 6 hour drive north.