Doing a rammed earth project will require a lot of back breaking labor.  Free beer and hot dogs will not be enough to keep friends on the job that long.  Also, the local available materials must be suitable.  My advice:  Really research this method or any method before tackling on your own. 

You might want to contact someone at Auburn University's Rural Studio in western Alabama.  A lot of my former architectural students spent a semester there doing basically inexpensive homes with recycled and donated materials.  Their professors might have some ideas to share with you.