Corbin do seats for tall or short riders riders too just need to specify when ordering. At 6'8"
@Steel is correct you need h'way pegs for a stretch. I do have the R3Touring original Triumph Longhaul Dual and the similar Solo Bucket with Comfort Pillion accessory seats but am unsure if they would improve the fit you have with the stock R3Touring Dual seat.
@BigNorm is a big bloke on a R3T too and he cut out and reshaped his own stock seat and made huge risers for his bars that I think he has now ditched or re-made stronger following his crash.
There are handle bar options from using the R3 Classic bars
T2043580 but with your height you may be happy with stock Roadster ones.
Classic
Aftermarket T bars are available from a UK forum member who has sold over 400 sets worldwide
@chandelierman he does batches periodically for about GBP135 for plain steel and posts worldwide.
My friend who makes the T bars has a few more in raw steel £135 plus shipping....Please delete if not allowed
NZ Thunderbike from New Zealand make a few versions in 1.25" and 1.5" NZ$600-700 (US$410-480)
The massive 1.5 inch tubing gives these T-bars the bulk to match Triumph Rocket III. Custom fit for the Rocket, dont require extra parts or modification of the bike.
shop.thunderbike.co.nz