I think 50 mpg from an 850 cc engine producing approx 115 bhp is about right. My 2012 675 Street Triple never bettered 52 mpg even when ridden at 55 mph down country lanes (yes, I know - who buys a Street Triple to do 55 mph - it was a mistake, ok?).
Windscreen - there is a company making screens that, they claim, use laminar flow techniques to reduce buffeting
https://shop.heroblobs.co.uk/pages/laminar-lip
On the other hand you don't like looking through plastic want wind protection but no buffeting. I think you may only get to pick 1or 2 out of those.
Seat - Corbin, Sargent maybe?
... but if the "magic" has gone then it's back to a dealer.
Plan B on the seat: Visit a dominatrix, get spanked, embrace the pain and the Tracer will give you fond memories each time you ride.
