I face the same problem of having to hide my antennas and worrying about the health effects of too much power. A horizontal antenna at a low height in my attic works against me because of the high angle of radiation. Instead I have focused on getting an efficient vertical system. Actually verticals work well IF you use elevated resonant radials. When I work the high bands I can get by with attic antennas such as dipole or mag loop. High bands are daylight bands where having something inside or in my attic is more stealth. But when the sun goes down, I can go outside with portable verticals that are better on the lower bands. I have used Buddypole parts like an erector set. I can erect a full height 40 meter vertical using a fiberglass pole on a tripod supporting a vertical wire. On nights when did not want to put up the big pole, I can use shorter whips and a screwdriver coil at the expense of some efficiency. I have a telescoping 17 foot whip, and using some buddypole arms, I can easily extend that to 22 feet, and then with a little inductance from a screwdriver base I am on the air. Then using appropriate sized wire elements and radials to handle the higher current, I can increase power.
Now to avoid the health problems of increased power, I can move the vertical out to the edge of my back yard about 50 feet away from my home, within FCC guidelines.
When I started experimenting with solutions for my HOA woes, all of this seemed like a hassle. But, once I got things worked out and organized, it takes me just minutes to put up, or re-configure antennas. I bought extra parts from Buddipole people, so I have antennas for every band already assembled with quick release mounts, so I can erect one when the sun goes down by just slipping it up on a tripod, or another support of which I have many outside in various places. I use two radials elevated per band. They are pre-cut for each band, and they are rolled up when not in use. When the sun comes up, they either disappear, or get shorter and more difficult to see for use with the higher bands.
So, my solution ended up with as an efficient an antenna system as I can get away with, a low angle of radiation, the ability to work all bands, the ability to move it all away from the house when I feel like a night with more power, and a mag loop in the attic for 40 to 15 meters when it is raining and I do not want to go outside to put up one of my verticals. I can also use both indoor and outdoor antennas at once with two rigs and work two bands, or two modes on one band at once. I feel very competitive now and it is not a big burden to deal with setting up different antennas. Indeed, I enjoy the flexibility to work many bands, and am just now starting to setup on 160 meters, the last band I have to conquer. At the end of the day, I no longer feel deprived of my hobby because of my HOA. My various antennas work very well, I have no concerns about power or safety, I have flexibility many hams with antenna farms do not have, and I have solved the problem of safely using high power.
So basically I have the ability to work all bands, with any power I want, and it all goes away or in my attic when not in use.