Like many people, I can't erect an antenna. Reviewing the rules, there is nothing prohibiting a flagpole. I have looked at a few online, but do they really work for HF? If I understand correctly, they are just vertical dipoles. When I was a kid, I used a 80m dipole with 40m traps, on 80, 40, 15 and 10 meters. It worked great without a tuner. Now there are several more bands. so... tuner? I'm not sure I could pull off an auto tuner at the base of the antenna. Can this setup work reasonably well, even at sea level?

Next, my house is on a slab. I would need to run the feed line underground, then up the side of my house, through a wall and into the shack. Maybe 70 to 80 feet.
What kind of feed line should I consider?

Thanks very much!