That my friend is why God gave us ape hangers. My latest ride is an '03 Sporty with a hopped up motor. Even with the mods the vibration is handled well at the feet with iso pegs, and the bars dampen the vibes to the point that I don't even run iso grips anymore.
I know sometimes it has to do with the length and location of the bars and pegs due to harmonics. Keep in mind it wasn't a deal-breaker complaint just noticeable. And I didn't do anything to work around it. I got use to tightening the throttle friction lock and take my hands off and flex them once in a while. Plus I had very short bars on mine. Ape hangars would definitely be different. I still love the Sporty as I said and actually don't like the later rubber mount engine version because they changed the shape of the tank they had for years....I loved that old shape and if I had the money I'd buy another early Sporty just to have.