I don't think that there are any forks that don't have bottom access to the steerer tube. ??

Plenty of fenders mount from a nut or expansion plug in the bottom of the steerer tube. I have one on an mtb it holds up fine. There won't be any reason to try and drill into the crown. As mention with a star fangled nut down there you can bolt on anything, any kind of fender can have a hole drilled into it and mount that way.
I've used double sided tape for things on bikes. It won't take much load bearing and it will wear out.