Being the antenna is elevated, I wouldn't expect 8 ft
radials to work worth a hoot, except for 10m.
They need to be resonant. The "same height as
radiator, for usable performance" doesn't really apply
to elevated radials, that need to be resonant. Only
ground mount, will that work ok. Yes, a hat will always
help, but I would just string it with cheap wire, if it's
hidden away in an attic. If on a roof, you could hang
sloping top loading wires, that sloped towards some tie
off point. Or you could use a fancier hat setup....More
$$$ though. BTW....In theory, it should be possible to
use loaded radials...Or maybe a 2nd loaded element to
complete the antenna as a psuedo loaded dipole. ?? MK