have you thought of using something like a super thin piece of electrical tape to wrap around the pivot to stop the rattling sound? (assuming these sound the same as smokies).
I wonder if you could do a hybrid...
Maybe a sphirical pivot bearing that fits inside a urethane bushing of some sort (larger size), with the pivot area of the truck machined to accomodate THAT...?
It seems like the pivot bearing would give easily well before the urethane would start to compress, giving you the precision turn, while having the urethane buffer as a shock absorber.
I was wondering, when I saw the pics... Beautiful work, btw. It just makes so much sense.
Can you just use a rubber isolation type riser pad?