Hello lovely plumber experts. I've 'fitted' a floor mounted cabinet with a basin. Waste is fixed height through the tiled wall. Have cut a notch in the back of the cabinet to get it flush to the wall. No space behind the cabinet backboard to plumb. (30-35mm only) Connecting a p trap, bottle trap etc means the exit from those is too high. Connecting p trap, bottle trap to waste hits the shelf. I do not want to cut into the shelf as the vanity was fitted FOR its shelf/storage. I'd prefer not to use a FLEXCON pipe. Any thoughts, ideas, solutions would be greatly appreciated. I have attached pictures. Any thoughts, opinions regarding the McAlpine Space Saver WHB-1 instead of the above?