Well, hold on! I see you have the superman tape, so I guess you'll be OK! :D I've had a similar problem with a Dragon 1/72 Lightning. What I can recommend to you is to do more dry-fitting, and then you can try sanding the mating surfaces, glueing a plastic shim here or there, or sometimes even bending a part slightly - tricks like that can drastically reduce the amount of filler that's necessary. On the plus side you have a very nice looking interior there. Good luck with your build and have a nice day
Paweł