Yes, that is exactly the way to do it. Sometimes a tile setter will set all the field tile and then put down a layer of thin set, let that dry and then put down the thinner tile. Building up the base is the key. If it's really complicated, you might want to find a tile setter in your area.

Thank you for your quick reply! That's a good suggestion. We are getting bids and one of the contractors commented that most likely the transition wouldn't be perfect (preparing me). I'm still talking to others so will definitely see how they reply to the question.

set the accent tiles that u have on a custom cut piece of hardibacker, depending on the tickness of ur field tile U could use 1/4" hardibacker . im a tile setter and thats usually what I do . is fast easy and makes the transition unnoticeable. :)

what is that stone on the tub?