9 speed shimano allows you to easily use their mtb kit to find triples and long cage RD.
This is definitely interesting, I've got a 9-speed LX RD kicking around and a 9-speed cassette, so I'm thinking that some Tiagra 2x9 brifters and a suitable rear wheel would allow me to at least try it out.
Sorry I should have been more clear.
9 speed shimano allows you to easily use their mtb kit to find triples and long cage RD.
But I still think there are merits to finding a road set up using 10 speed triple crankset and shifters (if you can).