Your flagpole project got my rememberer going.

Here's the comparison between (in our case) a 35' fiberglass pole versus a
high quality aluminum pole and why we went with the fiberglass.

Aluminum pole

Wind rating without flag: 100 mph
Wind rating with flag: 80 mph.

Fiberglass pole

Wind rating without flag: over 200 mph
Wind rating with flag: 155 mph

For us, the 80 mph rating was calling it too close, particularly if in a
winter Nor'easter and I forgot to take the flag down.

The installed cost of the fiberglass was just shy of twice that of the
aluminum.

Eisboch