There seems to be some conflicting advice about the hole size. Logic says, as you do, that the hole only needs to be big enough, whereas a Stans video suggests you file the edges down (for a better seating, I guess).
There seems to be some conflicting advice about the hole size.
I did see that too, in the end I just prick the hole and push the valve in (all tubeless installation were using Stan parts), the main issues were merely the tyres not mounting/not enough rim tapes.
Make sure you only make a tiny hole in the tape for the valve to fit through