Did mine last week and took all the stuff off the walls and "tiled" right to the window edge, under the face plates etc. My bath will be next and I plan the two walls, behind and to the rt, the shower is to the lt. I think it' a matter of preference, what do YOU like. Those look like the same "tiles" I used from Lowe's and I was told they are closing them out.
2000 F250SD SRW 7.3 Long Bed Extended Cab Air Bags
2014 Eagle 30.5BHLT
2007 Layton 245LF (sold)
196? Shasta 16ft
Learn from others mistakes, you'll never live long enough to make them all yourself.