Didn't you guys post this already here? Or maybe over on ADV rider ... where you actually get a response?
YES! you can get your TVIP in La Paz. You'll have to buy your Tourist Visa there as well. I don't think you will have to worry about getting your Passport stamped, but they may do it when you get the Tourist Visa. For US citizens, they never do this.
Baja is a Free Zone, so Mexico really doesn't begin until the mainland.
You may get stopped at Guerrero Negro and asked for Tourist Visa. They will sell you one there. Big Flag, military base there and most always a check point as you enter town.
Ensenada has never had an Aduana office for the TVIP form. But you can get the Tourist Visa there if you catch the guy there. Unless they've shut it down? Could be I guess. His office is by the port, near the huge flag.
Anyway, no worries. La Paz is good. Go to Ferry terminal, ask for Aduana/Bancjercito offices for TVIP. You may be able get it in Santa
Rosalia (also at Ferry Terminal) as well. Don't take that Ferry. It goes to Guaymas, is very slow ... and expensive. Sucks!