So I'm redoing a tight bathtoom. It's about 106" total. Left to right I'm going to be doing vanity (wall mount) 32", sink top may hang over an inch. Then 15" on each side if the toilet to code I believe. My question is if the shower is around 40ish do i need 15 off center to the shower door, the threshold, or the shower floor itself? Pic included.....just want to maximize shower floor. I wish I could do a curbless design but that probably gets expensive although I am doing a full demo and it'll be open to the basement. Anyway.....15" from center to door or curb which is 4ish inches? What's the right way?