Agile works fine
A lot of design methodologies work fine in the hands of experienced coders. By experienced I mean they've been through the process from top to bottom a few times.
1)Oh - and management has to have done that too. Which is where most things fall down.
I've used the 'write the code in meetings and when no-ones watching and then present it as an option" approach a few times. Best to bring out working code that's not 'a la mode' when they're desperate for it.
But the best approach is normally to subtly get the customer to accept something that's already out there - its what they want most of the time and the chances are only an experienced developer will recognise their problem is really as old as the hills. But see point 1) above.