renovating a bathroom to add wet room for tub & shower
The size sounds large enough for a shower. Have you thought about a ceiling mounted shower? The shower coming straight down there may be less splashing compared to a wall mounted shower. I usually install 2" shower drains but have installed 1-1/2". I find the size of the drain opening like a larger 4" square grate compared to a standard 2" round makes the biggest difference with a shallow pan or slope, more area less water back up.