If you have access to Dragon, get a Monk's belt (you're a Wis-based caster using wild shape, so not a bad choice anyway) and take Beast Strike from Dragon 355. You get to add your slam damage to all your unarmed strike attacks, which essentially allows you to use your iterative to deliver slam attack damage, plus the damage boost of the unarmed strikes of whatever (virtual) size category you happen to be.
"But wait! Unarmed Strikes suck!" ...Aptitude weapons, my friend. Aptitude weapons.
Help me connect the dots here. Are you suggesting an aptitude weapon to add the slam damage onto something like a mouthpick weapon used in wildshape?