I bought the bike used with less than 200 miles on it, but the previous owner has replaced the bar ends. I pulled them off & realized exactly what you said about the weights. Not sure how far in they'll go & didn't know how to 'attach' them to the expansion clamp of the new mirrors. I'll look into these You suggested. Do you know the approximate diameter and width of the grooves?
The bar ends I suggested fit mirrors that have 22mm clamps. I don't know how wide the puig ones are.