Chris,
You've done so much to your car I think you can do it. But you will need a sturdy press to replace some of the bearings. My son rebuilt the rear end of his 42 year old pickup in his garage including setting the backlash and getting the gear engagement right. He broke the pinion. He is on his second type of limited slip and changed those himself. So with the right tool and some mechanical ability is is fully possible to do it yourself.
I looked at this briefly to see if my son's Ford pickup experience seems reasonably applicable to BMWs:
https://www.eeuroparts.com/blog/1076...l-rebuild-diy/
I decided they are pretty similar, ignoring the fact that pickups are solid axles. The article recommends just taking it out yourself and letting somebody else press the bearings in place and set the backlash. That would be an option. My son found that process frustrating but he got it done. You have to try different shims and the assembly process to make the test is not terribly easy. But he got it done and it works fine.
I agree about checking on parts availability although I suspect they can be found. Car manufacturers do not make caged bearings and the suppliers who do make them have catalogs. A quick google search also showed some rebuild kits but I did not look at them closely enough to see if they are applicable.
Jim