The usual post editor can be hidden after all! Without removing support for it when registering the post type.

Add the following code to the constructor for the meta box class described in previous posts on creating custom meta boxes.

//hide editor if adding a new post of sermon type
		if( isset( $_GET['post_type'] ) && 'sermon' == $_GET['post_type'] ) {
			add_action( 'admin_head', array( &$this, 'hide_editor' ) );
		}

Add this as a function in the class.

	function hide_editor() {
		?>
			
				#editor-toolbar { display: none; }
				#editorcontainer {display: none; }
				#quicktags {display:none;}
				#post-status-info {display:none;}
			
		<?php
	}

The code for hiding the editor was taken from http://wordpressapi.com/2011/03/19/hide-wordpress-visual-editor-html-editor/