This is a common installation location as this is the plumbing wall. Distance of the steam head from any area you may come in contact with while the steam shower is is important. You don't want the steam head too close to anything you may touch while steam is coming out.
I would suggest calling a steam bath specialisthttp://www.steamsaunabath.com/catalog/project_coordinator.php
with the details of your installation (height of steam head, height of shower controls, material of shower controls, etc.) for specific recommendations.