I gather you are not going to be commuting on this one?
The long haul seat on my Touring is probably th most comfortable factory seat I've sat on, on the other hand Corbin seats saved two other bikes that were almost unrideable with factory seats, so I'd be hard pressed to call it.
Yeah true but Longhaul seats and their upholstery/padding etc are really only available for the R3Touring range and could or have been refitted to a Roadster seat pan. People confuse them with the R3 Standard/Classic and early accessory dual seat versions which also fit Roadsters and had various names in the accessory catalogs before the R3Touring was released.
Edit: I have actually found a Fowlers UK where the 'Longhaul' is used for a Standard/Classic/Roadster seat
Fowlers Parts are the largest UK supplier of genuine motorcycle parts & spares for thirteen manufacturers of motorcycles. Offering next day delivery (UK) on orders made by 5pm.
au.fowlersparts.co.uk
They only use it in reference to the complete kit with rider's backrest
Seat, Dual, Backrest Kit
A9708164 is used for the whole kit with backrest rather than as just the seat below

R3 Standard/Classic/Roadster accessory seat range and part numbers from Triumph Accessories catalog:
CLASSIC TOURING SEAT - DUAL A9708164
For use with ADJUSTABLE RIDER BACKREST A9708160
DUAL SEAT KIT - CLASSIC A9708059
TOURING GEL SEAT - RIDER A9701142
TOURING GEL SEAT - DUAL A9701141
ROADSTER GEL SEAT - DUAL A9701140
LOWRIDER SEAT - RIDER A9701151
TOURING GEL SEAT - PILLION A9701143
I do have a brand new unused CLASSIC TOURING SEAT - DUAL A9708164 with the ADJUSTABLE RIDER BACKREST A9708160 available in the USA for sale. PM for details.
R3 Touring accessory seat range:
LONGHAUL TOURING SEAT - DUAL A9700209 fits ADJUSTABLE RIDER BACKREST - LONGHAUL A9708158
BUCKET SOLO SEAT A9708162 fits ADJUSTABLE RIDER BACKREST - LONGHAUL A9708158
TOURING SEAT GEL - DUAL A9700500
COMFORT PILLION SEAT A9708163
Bucket Solo A9708162 & Comfort Pillion A9708163 were later sold together as the Longhaul Seat Replacement Kit T2302130
for the no longer available/sold LONGHAUL TOURING SEAT - DUAL A9700209.
I also have all of the R3Touring seats above available NEW in factory boxes or the solo and pillion used as well here in OZ but the Solos are very light and will post to the USA for about US$70.
I have one used ADJUSTABLE RIDER BACKREST - LONGHAUL A9708158 that fits the Bucket Solo or the Longhaul Dual and a I have a brand new old stock LONGHAUL TOURING SEAT - DUAL A9700209 too.
PM for details
LONGHAUL TOURING SEAT - DUAL A9700209