I won't engineer the part (except for the CAD work) as it's not my field of expertise.
Why do you think the bearing will fall out under braking ? I was under the impression that under braking (and heating) the thermal expansion would exert even more pressure (preload) on the bearing.
Here you...
I know that wheel spacers/adapters are made of aluminum, but could a wheel hub made of aluminum too ? I haven't seen ali hubs for cars, only for motorcycles.
This could be a great way to reduce un-sprung weight and rotational mass.
Are there any reasons not to use aluminum (like 7075-T6)...