Are you now convinced that you really need to do this! While there are lots of different opinions on how to do this, we all will tell you DO IT---it is more fantastic than what you saw on the video.
Just start writing all of us and then decide what is the best way for you.
We went, and it was the trip of a lifetime. But I don't know if I would take an RV out to the coast -- the road is too rough. I would leave it in San Ignacio and take a van with a tour operator, or take your 4x4 toad if you have one. (My Pathfinder had no problem at all.) There is an outfit that runs an "ecotourism camp" on the bay -- Kuyima -- and they have vans, and huts with beds. The bathrooms were eco-friendly outhouses, but not too bad, really. They had food, which was decent but not great. The boat guides were very knowlegeable. Kuyima was expensive, but worth it, I think. See www.kuyima.com/whales.