Well, yeah, I tried that with Banjozilla and it helped reduce the feedback problem. But it also took away the banjo sound. It just sounded like an electric upright bass. It helped me figure out what was causing the feedback. It was the head moving from sound in the air, then making the strings vibrate. Stopping the head from moving stopped the feedback, but it also killed the banjo sound.
And yes, you could build an electric bass with a big round wooden body and a fairly rigid wooden disk on the front. Paint the disk white. An electric bass designed to look like a bass banjo. Send the signal through a digital synthesized clip of a banjo-like sound. A fake bass banjo. Is that what you want? I don't.
If I'm going to build a Bass Banjo, I want it to have a real functioning head, and have a real banjo sound.