I find the idea intriguing, but also see some difficulties: you would need to be careful to prevent an aft CG condition. Also, you would need a different canopy or the back seater would sit very low and have a poor view. The higher canopy at the back might have an adverse effect on the vertical stab & rudder, similar to the P-51 switching from a razorback to the D model bubble canopy.
The elevator control and rudder cables pass thru the center tunnel, which is above the seat pan, so you would be modifying the primary flight controls, never a good idea. One thing leads to another, I know, I'm paying the price of modification with my RV-8 project.
My personal opinion is that John Thorp was very talented and built a carefully integrated aircraft that requires especial care to modify, not like hanging a huge radial on a Stearman.
