Off the top of my head, it seems that one of the things to do is to go ahead and look at correlations with self-report measures. However, you'd also want to look at other ways of assessing the variables you're assessing through scoring responses to projectives. I think that cognitive psychologists (i.e. academic psychologists who research cognitive processes) have some laboratory procedures for assessing schemas and other cognitive variables. I seem to remember studies using the Stroop Test, reaction times, etc. but I don't remember the details at the moment. If I remember right Rich McNally has published some studies of objective measures of cognitive variables.

It wouldn't be an easy project but if your goal is to go into academia it might well be a topic where you can do some innovative and publishable research by using a masters thesis to set the stage for a dissertation on the same topic. If your goal is primarily to go into clinical practice, it may be a bigger project than you'd want to take on.