TST has some nice Bar Ends that double as sliders. They screw right into the end of the bar weights in the R3s handlebars. Easy Peasy. $18.50 plus shipping.
https://tstindustries.com/Bar-Ends-KTA-Y1.html
The pain you have is probably from compression of nerves in your palm. Usually starts with tingling. If you have it every time you ride, you could end up doing some nerve damage that could take a long time to heal.
I haven't noticed an issue with vibration in the R3s bars with the TST bar ends. Heavier ones are available if you really need them, though.
http://www.hvmp.com/
Video review (more of an install video than a review of how well they work) of them: https://www.youtube.com/watch?v=53KrSFLYWdY
These weigh 17.2 ounces each! If these don't stop any bar vibration, nothing will!
Another option is finding some gloves with gel pads in the palms.