Last Subway to Baiyun from Canton or should we cab it?

Canton Tower closes at 23:00 (11PM). Will we be able to get the subway back to the airport? What time is the last train. Also if we ended up needing a cab back, is it was to get a cab back to the airport at that time? Anyone have a contact for a cab service we can call if not? We may want to just see the Pearl river while there. Is it difficult to get a cab after 23:00? We cannot afford to be stranded until morning. Thanks for your help. Anyone know how much a cab is?