Keep the custom messages set for each level under Membership >> Membership Levels and combine it with the PMPro Approvals status.

custom-level-confirmation-message-for-pmpro-approvals.php

function modify_status_from_confirmation_message($confirmation_message, $pmpro_invoice)
{
	global $current_user, $wpdb;
	
	$approval_status = null;
	
	if(class_exists('PMPro_Approvals'))
		$approval_status = PMPro_Approvals::getUserApprovalStatus();
	
	if(!empty($approval_status))
	{
		$confirmation_message = "<p>" . sprintf(__('Thank you for your membership to %s. Your %s membership status is: <b>%s</b>.', 'pmpro-approvals' ), get_bloginfo("name"), $current_user->membership_level->name, $approval_status) . "</p>";
	}
	
	$level_message = $wpdb->get_var("SELECT l.confirmation FROM $wpdb->pmpro_membership_levels l LEFT JOIN $wpdb->pmpro_memberships_users mu ON l.id = mu.membership_id WHERE mu.status = 'active' AND mu.user_id = '" . $current_user->ID . "' LIMIT 1");
	if(!empty($level_message))
		$confirmation_message .= "\n" . stripslashes($level_message) . "\n";
				
	$confirmation_message .= "<p>" .__('Below are details about your membership account:');
	
	return $confirmation_message;
}

add_filter( 'pmpro_confirmation_message', 'modify_status_from_confirmation_message', 10, 2);	


function my_init()
{
	remove_filter( 'pmpro_confirmation_message', array( 'PMPro_Approvals', 'pmpro_confirmation_message' ) );	
}

add_action('init', 'my_init');