One trick: in weekly 1:1 meetings most employees will start by just discussing their current issues. Instead, start by talking about what you accomplished last week and its value, then move on to what's next. This is still a natural conversation (discussing the past, then future), but it makes your value and results much more visible.
As the saying goes, "change your company or change your company." That is, if the ample evidence that productivity typically peaks somewhere around thirty hours a week doesn't convince your boss, quietly start shopping around for another job where the management aren't bozos.
