By 2x8 planks do you mean 1x8 subfloor or 2x8 floor joists? If you are 3/4 inch below slab I believe I would but 3/4 inch t&g OSB on wood floor and then float 1/2 inch Hardi board over entire area making sure to straddle wood to slab joint with the Hardi. Get that joint very flat as 16x16 tile are very unforgiving

I'm with LWO: tear out the ceramic. It will be less trouble than pulling out/reinstalling the baseboards, potentially cutting the door down due to increased floor height, and boxing in the vanity, making it difficult to change out down the road. A clean slate would be my preferred option.

I think you would ruin the ceramic tile for good. For the next remodeling it would be a matter of removing tile and planking. R u concerned about removal cost? Those guys do that in a blink, so not a big budget component. Yes, it is messy and you'll be dusting for weeks. Even so, my professional tile setter sprinkled water when removing old tile which reduced a lot of the flying dust. You could do it yourself to save $ but the time and effort are not worth it, IMO Another consideration is that when you leave tile and add something on top, you raise floor height and will have to trim doors, etc. It is not a cost saving strategy.

If you are spending ALL THAT money for CoreTech, you might as well get the floors level! Another $2/sf to remove the tile should be do-able. Remove the tiles and you NEVER have to deal with them EVER AGAIN. And just to let you know, tiles will often sit 3/4" HIGHER than the subfloor. Now IMAGINE putting the 1/2" CoreTech over that tile. The drop is going to be MORE THAN 1 INCH!!!! Toe stubber extraordinaire! Remove the tile, carpet and laminate and do this the *right way. The way that makes sense. The way that will make life SOOOOO much easier in the future. Why sacrifice the look of your home (1380sf) because you do not want to remove 300sf of tile? It doesn't make sense. It would be in the category of "Cutting off your nose to spite your face". Yes, jacking out tile is dirty and dusty and not a lot of fun. But it happens every day all over the world. It is the right thing to do. If you leave the tile, the transitions through a few door ways would be SIGNIFICANT and ANNOYING. Or you can RAISE the floor heights in the other 1080sf (imagine $3/sf to raise up the 1000+ sf...) just so you do NOT have to remove 300sf of tile. Hmmmmm. That doesn't make any sense at all. Please take out the tile. You will be SOOOO much happier that you did. Trust me.