He can be very accommodating - but experience has taught him that if you go too wild with ideas, then that's when instruments don't turn out as expected.
He's done everything that I've ever requested on my basses - and some of those features are no part of his add-ons - e.g. laser cut back plates (so the grain on the back perfectly matches up) and engraving was a first, on one of my basses.... along with phantom power, LED light up logo headstock on a Spitfire, chrome decals, nickel nut, solid facings on a through neck...
Just talk to him. It's when you start going down weird body shapes he's likely to raise an eyebrow - as he shapes have been worked on to balance perfectly.