Some useful stuff here, but if "stealth" and avoiding HOA rules which don't allow antennas but do allow flagpoles is really the issue, then fibreglas poles with a wire and such things aren't useful suggestions.
For a flagpole to be a flagpole, it needs to fly a flag at the top, which means a heavy top load (especially in the wind, when that 8 ounce flag now weighs 50 lbs) with a rope to hoist and lower it, a halyard, etc. Like a flag pole.
Cheap fibreglas or PVC masts aren't going to do this. A real flagpole can.
It needs to be aluminum or galvanized steel or something that can actually support a flag in the wind at the top, and unless illuminated at night (per "flag rules") can be lowered at dusk and raised at dawn and all that.
Thickwall aluminum tubing can do this job. Insulating at the base is really easy. Post hole digger and a few bags of premix concrete + water can install it in an hour. Use a level.
