thanks for the private message .. I cant answer it due to my less than 50 pints ... yeah ..
anyhow
get the long seatpost and cut it to length, it will be affordable and light as you cut half off . its a good seatpost and well worth the money ... and an aber hallo to move the handlebar back ...
( keep the other seatpost and seat, if you want to sell the bike or have somebody else ride it :-)
Best Thor