I can visualize that. Thanks for the clarification.
Looking forward to seeing progress pictures to see your ideas come to life.
For reference purposes , I made two adapters for my K series bm'. The first one steel as I had nothing to compare it to from first hand experience. The second one from alloy. The weight/inertia difference is noticeable. Not a deal killer , but there none the less which could be addressed by using a lighter rim.
These were used in conjunction with the same 15x4 steel rim.
I'm diagonally parked in a parallel universe.