Narrow tub overflow drain needed

[BobHu]

I am remodeling a shower next to a whirlpool tub. I plan to tile the short wall between the tub and shower, which will have glass above the tub deck. The previous shower enclosure had a thin sheet of cultured marble there. Now that I have removed the cultured marble, I see that the tub overflow drain does not leave enough room for cement backerboard and tile below the tub deck.

Various solutions are possible. One might be a narrow, maybe oval-shaped or rectangular, overflow drain that would take less space. Is there such a thing?