Ok, there's a few tricks that may well help both of you.
First off, remember that vibrations are a fact of life with parallel twins, learn to love it...hhehe
Ok, there used to be a product called 'Bar Snake' that could be run thru your handlebars that was as far as I know just some heavy material suspended in a rubberized plastic. Worked OK.
If you aren't running your wires thru the bars then you're in luck. Seal up one end with a plug, pound in a hunk of cork...whatever, just be sure it's secure. Fill your bars with regular old sand. You'll want to pour it in til it's more or less full, then tap the bars for 10-15 minutes to allow the sand to settle. Do this a few times, topping off your sand fill then plug the open end you were just filling.
This adds not only weight, but will drastically lower the bars resonant frequency and should take care of the vast majority of your vibe problems. If you're still dealing with buzzy mirrors, then a pair of stainless bar end weights can be hung off the ends that'll kill a bit more.
If you're running wires thru the bars, you'll have to be satisfied with bar end weights.
I've used this method for quite a long time and it generally takes most of the problem away.
Also, if your bars are rubber mounted, make sure the bushings are in good shape, try more or less tightness on the mounts.
I'm running clip-ons on all my bikes and the sand/bar end weight method even helps with them.
If you need help with the weights, I run a fabrication shop and can probably help you out. You might also try one of our many parts suppliers for options.