August in Cabo should have warm water, hi 70s low 80s. The vis is just ok but sometimes it's stellar. I hope you get to see the sea lions, it's so much fun when they play with you. I use Amigos Del Mar most of the times I've been to Cabo. They have a large trimeran with lots of places to put your gear and walk around the boat, the rental gear is in good shape, and the DMs know the dive sites and are safety conscious. If you get a chance to go to Cabo Pulmo, it's worth the ride there.
What ever dive op you use, take a look at their boat on their website, a lot of the OPs use a water taxi (no oxygen, safety gear or place to keep your stuff.)
Have fun.