Ham radio operators have faced this problem for decades. The problem with lightweight stuff is you never know when the downdraft will exceed the rating of the pole. And what you hang off the pole (windloading) makes a lot of difference. I'm not sure if flags are rated, but antennas are and I don't recall seeing a windload chart for various anemometer or complete stations..
I have a bunch of pesky trees (hate 'em when they shed billions of oak leaves, love 'em when they shade the house from too much sun in the summer) that keep growing. When I moved here 40 years ago, they were much shorter. Strange how that works.
Nonetheless, as stuff has gone up on my tower, I have lost the physical ability to safely climb. Finding a climber to work on stuff is harder and harder now that TV antennas aren't needed for much of the entertainment we get, even HDTV off the air. I really get ticked when a sensor such as an anemometer bearing suddenly needs attention and it is way the heck up there.
I can recall going to Dayton, OH Hamvention for many years and spending a lot of time looking at fold overs and telescoping towers. Out of my price range but neat, and to be accessible, they are not as strong as good old Rohn 25G or 45 G tower, but certainly something that if I knew I was going to live another 10 years and devote a lot of time to sensors on the towers, I'd give it some thought again.
Dale