Tolga, thanks for posting the images.
From what it looks like, the clear gunners glass looks like it needs to be slid forward to close out the obvious gap along the front edge where it butts up against the vertical fuselage mating surface and make the aerodynamic fairing in line with the base of the rudder. I can't tell exactly where the interference points are but its definitely sitting too far aft. You might want to consider cutting the vertical fin off (or, if you are skillful enough just the rudder would be an even better idea), filling the gaps around the tail gunners glass, and then re attach the fin. You could beef up the joint internally with some lengths of plastic rod if needed. I think you will be able to get a better view of what is getting in the way, too. Remember ramming sheet plastic into any remaining gap is a perfectly acceptable way to solve the problem. But you need the sanding tools to be able to get in close.
That particular fin-stab junction traps you between a rock and a hard place. With all the sanding mayhem you had to do to get to this point, i'd suggest you take it all off and either rescribe or draw new lines on with a pencil. The ribbing on the fabric covered control surfaces looks overdone anyways.
I know there's a fix to all of this, but its gonna take a bit more work.
david
