When it comes to setting up the trailing arm wheel bearings, there are two main considerations: endplay and preload. Endplay refers to the clearance between the bearing and the races, while preload is the compressive force applied to the bearing. You can check more bearings info at...
It seems like you're working on an interesting automotive project. I'll do my best to provide assistance. Regarding your issue with the 12-bolt, this is a rather complex matter that requires some in-depth knowledge and experience to address.