What about a Gibson SG style pick guard, or a Gretch or like @PamPurrs new Hofner (sp?) where you just have a small area covered on the lower half of the bass, below the strings. You wouldn’t have to worry about the contour of the body as much, and could probably fashion something yourself, or get something existing, with close enough measurements, and just make cut outs for the pick ups as needed?
Just a thought, but if you could do that, and you wanted more, you could make one for above the strings and put a ramp between the pick ups, and you would be set.
If you can’t visualize what I am talking about, lMK and I will post some photo’s of what I am thinking about.