Number one …relax. The wrist thing doesn’t help but unless your trying to run and gun through town for 4 hours your wrist should not be hurting at all. The lever adjustments will only help at stops and clutch control for leverage more then anything. You may also need to consider looking into handle bar risers with a pull back to get your arms in a more relaxed position to allow you to loosen your grip up a bit. I had to get a 2″ pull back on my Vulcan so I could allow my arms to bend a touch more and take the weight of my arm off my hands and wrists.
Depending on your riding habits and style would depend on recommendations. Check your reach, your arms should be able to be in a relaxed state. Try adjusting your starting position of your wrist for acceleration so you can account for the movement for when your in cruise stretches. That away your not under the grip or over reaching it. If its a muscular thing ….. workout the forearms with some simple weighted forearm curls. Or even forearm band or whatever their called…. like the tennis elbow folks wear. You can also look into a cramp buster. Though I don’t recommend it til after you get smoother on your take offs.