A solution to NOT drill your track forks and have a normal front brake nonetheless

The forces due to braking would not be "redirected into a vertical pull".. Braking would put the star nut or whatever holding mechanism under shear load, not tensile. Maximizing surface area at the interface and mass at the joint is probably most optimal, try to minimize potential stress concentrations. That's not to say a star nut wouldn't do the job!

I think the tensile load wouldn't actually be very much.

ottbot, see above, if there's a bit of a stem fitting into the steerer snugly, then there is no other movement possible for the whole thing but up/down the steerer tube, therefore the force is actually redirected into a more or less vertical pull.

In the end, those carbon-suitable wedges will probably work as well, but might be not as slip-out proof as the starnut, and it needs to be checked if they might cause more problems than the starnut due to the variations in diameter at different track forks bottom holes.

The last problem is simply clearance as others have mentioned.

A lot of track forks have very tight clearance.
In order to allow tyre clearance, the plate will need to be pretty thin, which increases flex.
A front brake can exert a lot of force, which will flex this plate and give poorer braking power.

This can be helped by keeping the plate as close to the crown as possible obviously, but again, there are several types of crown with differing widths, which means you'll need to allow for the widest.

No worries, I have a solution for that which I will show later in the evening. Zero clearance.

There may also be an issue with the plate 'rotating' slightly under the crown.

Not all brakes pull evenly on both sides, either due to spring tension or poor setup, or wonky wheels, or uneven pad wear etc. Again the braking force and vibrations due to flex in the plate could possibly cause some slight rotation and hence brake rub.
Slight rotation back n forth could lead to loosening.

Just trying to cover all eventualities. :]
This could again depend on the shape of the front of the fork crown.

Even though it's not an actual problem, it will be resolved in the next design as well.

Magnus, you are clearly dead-set that your idea is the best.
However, you have missed the point that the SFN is designed purely to offer a temporary and rudimentary anchor for preloading headset bearings. Once you fit a stem correctly the star nut/top cap arrangement becomes largely redundant.

Ed "uncle bulgaria" scoble's idea is better in my opinion and tynan's points are completely valid.

RPM, I am not "dead-set" at all, I pay attention to every comment made and reply adequately. I would appreciate if you would read all my comments first. I already admitted that dmczone's mate's short stem addition to the hanger will improve the design, of course. But, any solution based on a normal quill stem (Ed) does not tighten the piece against the forks, and is therefore not suitable.
Regarding tynan's points, see my reply to him and to ottbot, above.

jetski