And honestly, I'm not so sure much of what I'm hearing on 20 through 10 is the bandnoise.
<SNIP>
Most days, right now, 40 sounds pretty good but the minute I go to 20 the noise is generally unbearable. Even on a battery.
“Band noise” is going to be local electrical/electronic “fog”. If you take a radio and antenna out into the country, you will find the noise drops to zero.
You need a step by step approach. As earlier replies, do you pick up the noise around your locality? A shortwave domestic transistor portable radio can help, maybe you can even pick up noise on a medium wave pocket radio for a discreet walk around. Also there is a DF flag antenna project in March 2021 QST that looks handy.
73 Dave