And then come those stating that what makes the sound of an electric instrument are the pickups (and preamp).
I'm saying it loud for more than 30 years : an electric bass (or guitar) is before all an acoustic instrument. If it doesn't sound unplugged, it will not sound plugged...
You can try this to add mass to your headstock and move the frequency resonance just enough to suppress the dead spot : https://m.thomann.de/gb/fat_finger_guitar_chrome.htm
Christophe LEDUC once told me, a very long time ago, that all instruments have a dead spot, even a Steinway piano or full graphite instruments, but the work of the luthier is to "hide" that dead spot. That said, he is an architect before being a luthier, knowing all these facts...