I can't figure out the orientation on your pictures. Is your set up looking like this, viewed from the top?
Oui, Alain. You're looking straight down into area under the dinette bench. The tank can be installed on its side or vertically and because there's a bladder inside the tank empties completely for winterizing. There is some distortion on the divider wall photo (it's straight up & down) but it looks like it's slanted. Make sure you loop the water line, too. You'll get some slack, if you need it and it reduces the vibrating that RV diaphragm pumps make.