WordPress Visual Composer Mods

functions.php

function vc_update_defaults() {
	// Default single image to size "full"
	$param = WPBMap::getParam( 'vc_single_image', 'img_size' );
	$param['value'] = 'full';
	vc_update_shortcode_param( 'vc_single_image', $param );

	// Modify button 2 styles to use custom colors
	$colors_arr = array(
		__( 'Custom Color #1', 'js_composer' ) => 'custom_classname_1',
		__( 'Custom Color #2', 'js_composer' ) => 'custom_classname_2'
	);

	$param = WPBMap::getParam( 'vc_button2', 'color' );
	$param['value'] = $colors_arr;
	vc_update_shortcode_param( 'vc_button2', $param );
}
add_action('init', 'vc_update_defaults', 100); // Visual Composer Defaults


// Remove Button 1.  Rename Button 2 to just "Button"
vc_remove_element( "vc_button" ); 
$vc_button2_settings = array( 'name' => "Button" );
vc_map_update( 'vc_button2', $vc_button2_settings );

Saved me a lot of hunting, cheers Jaybuys.