Hi Thal,
This is a late reply and hopefully you have already found what you are looking for on the Kona side, but if not Leleiwi in Hilo has a large resident turtle population that includes a regular "beauty salon" with multiple turtle cleaning stations, commonly with groups of turtles being cleaned at the same time in an area of the reef about 50 feet square.
However, I don't recall seeing many/any wrasses cleaning the turtles? The turtles are there, the wrasses are there, but can't say I've seen them together. We usually see "kole" cleaning the turtles as in Halemano's pictures above, sometimes yellow tang, or both.
Locating the cleaning station at Leleiwi is easy. From the entry, swim straight out to the drop off, turn right and follow the reef at about 40' depth. After swimming maybe 100 - 150 yards(?) you'll find a large area of sloping reef at 40 - 50' depth with a group of turtles laying on the surface of the coral being cleaned. They are almost always there. Some divers call the spot "turtle city".
The weather over the past several weeks has kept me out of the water here in Hilo, but hopefully with the current calm we've had over the past couple days I'll be able to get back in the water at Leleiwi this weekend, and if so I'll check for wrasses and let you know.
Good luck & Best wishes.
Edit: Bill, the owner of Nautilus Dive Center in Hilo would be the guy to ask about Leleiwi. He has literally thousands of dives there, is a regular "turtle rescuer (from fishing line), and if there is any "wrasse-on-turtle" action going on he'd know about it