This is a picture of the original bathroom. The vanity size will be retained. The bath/shower fiberglass insert will be replaced by an alcove tub with a shower (plumbing remains on right side). I will use a shower curtain. The large mirror, lighting, and wall cabinet are gone.

The countertop will be quartz (1 1/8” thick), with a backsplash of the same material (3/4” thick). I want to extend the quartz backsplash behind the toilet, down to the floor, and then over to the edge of the tub. Beginning at the tub edge, porcelain subway tile (approx. 2.5” x 9.5” rectangle will wrap around all three walls ). These tiles are 5/16” thick.

There is an inspo picture at the end of the post.

How can these two materials of different thickness be transitioned? Here is an idea of what they would look like at the abutment (quartz left/tile right):

Normally, the tile would have a vertical Schluter strip from top to tub surface on the outer side. The quartz will abut the tile for some of the tile’s length.

The quartz will have some sort of edging (normally in my house it would be “heavy pencil”). Could the abutting vertical edge of the quartz be rounded or beveled in some way to serve as a transition?

Or do you think this idea won’t work at all? (If this doesn’t work, there will be only painted wall behind the toilet, between the counter and the shower tile. I won’t extend the shower tile over to the countertop. The shower back wall cannot be bumped out.)