I think the RA spacers are "New PETG plastic spacers" which is pretty much 3d printed plastic. Im not sure how reliable they are for long term but Im not risking it.
I ended up using the supplied aluminum feet that came with the Bravo rack. I did however used butyl tape to seal the feet into...
Were you able to find a different mount?
I just ordered the Sherpa rubber mounts for the uptop bravo. Wish I read this first before I ordered though, I'll try to see if I can mod it somehow but man that's not looking to good.