I agree that Bahia Falsa is probably the best bet close to
La Paz. But because it is close it can also be quite busy. The good news/bad news is that July is very hot and there are not many people out sailing.
As noted, Coromuels are an issue and Ballandra can be particularly bumpy, particularly in the area that is still open to anchoring. Weekend evenings can be noisy as well with beach parties and the like.
Costa
Baja is a very nice marina (although a bit windless which is good during
hurricane season but not good when it is super hot). A night there and an early start to Espiritu Santo might make sense. As noted, getting away before dark could be tricky.
Some people anchor in Pichilinque, next to the industrial/ferry port. Its right next to the highway and I would expect it to be quite noisy. But it is really close to Costa Baja.