Don- I sure hope your boss listens to you. He must not be aware of the asset he's acquired, when he hired you.
Trees are just about the dumbest use of directional and yardage mark assistance accoutrement in the game, (save for boulders) unless the trees are huge old monsters that point the way and are almost completely out of play, ala The Preserve.
The barber poll serves the dual use you've chronicled and therefore, are efficeint,and hopefully low maintenance (lower long term cost) But also they assist in pace, by making the virgin not have to use their nose, I mean brain.
Pete Dye uses them all the time, does your boss think he's some slouch?
Important to use contrasting enough colors, Maybe even shapes of the lines painted, on the different poles. If your course is on that severe a site, there are likely instances where aiming poles might be needed at longer distances. The typical 150 pole is usually green and white with staright line segments. What I have trouble with is when they use blue for the 200 with the same line pattern on the stick. It sometimes is too close in color, and I get screwed because I was lulled. Grant it, I was unaware, but often on steep terrain the deception is believable. I just hate being fooled because of the closeness in color. Perhaps a true barber pole, with that swirly pattern would differentiate and eleviate the problem and subsequent complaints.
Just tryin to help.