Thanks! I think I will go for a laser printed decal then, as that seems to be easier to apply and I feel like I tried enough new things in this build already.
So for the next days/weeks I will come up with a design of the signature using a tablet pen and said tablet. With that I should be able to make it look almost calligraphic.
I will also continue to increase the grit between the tru oil applications - I am already using micro mesh pads and it's starting to be a very soft glossy finish.

I also got some bat-fretboard stickers and am wondering if I should put them on and secure them with a bit of spray can clear coat, like I did with the rest of the fretboard before. I have heard that these kind of fretboard marker stickers are pretty durable, so maybe that's not necessary.