Of that 300 to 600 mile radius, can you communicate with someone at 10 miles or 25 or 55 or 90 or ...?40 meters with a homemade dipole about 6 feet above ground (NVIS) works nicely for me. I can usually cover a 300 to 600 mile radius with 100 watts or less.
Is the antenna location on a mountain?
A 40m dipole is almost 70 feet long. That might be a hard hide from the HOA.