Hmm. This may be a long shot but perhaps there is a way to replace the rubber washers that the bars are mounted to with something thicker or maybe softer?
Another thing that might help a little is using a slightly lighter weight fork oil. That will make the ride a little more plush on bumps but don't know much it would effect overall vibration.
Just for comparison may I ask what bike you had before your Vulcan?
2009 1700 Nomad (Black)
OPT7 LED headlamp
Painted brake disks
Kawasaki light bar
Scootworks bar risers & engine chaps
RAM phone mount & drink holder
Kuryakyn speakers & AC outlet
National speedometer cowl
Wolo air horn
Oxford heated grips
Vaquero engine emblems
Mustang touring seat
Irons in the Fire rack
Kuryakyn Triple Play tail light
Cobra Tri-Oval exhaust
LED custom driving lights, accents, and turn signals
Goodyear Tripletred rear tire (205-16-60)
Ivans ECU flash