I know that it is recommended that a (shower and such) flange rests againts cementboard but that would result in my flange raised above the tile more that I'd like so I decided to tuck the flange into the cementboard so that, in the end, it is more flush with the tile. As a result, I have a small gap between the flange and the cementboard, about 1/8" on average.
I did all the prep work but will be outsourcing the tile work. My question is, will the tile guy be able to work with this gap as is and still get the tile to go up to the flange (then maybe caulk or grout around) or should I reinforce it with mash tape and fill it with something like thinset or some product that comes in a caulking tube? I do have the luxury of access from the back (which is where my utiliy room is) and could reach to set mesh on that side.