I've done this before. It's a good strategy and the only one as far as I know.
The voucher is issued for the fare difference (minus change fee) when you ticket the inexpensive A-B, so whether you ultimately board or cancel the throwaway flight is irrelevant. I'm not sure if the voucher would also be transferable, which would be an added bonus.
Last edited by lrdpenn; Apr 19, 2016 at 10:31 pm