I feel you on that. I'm 6'4" myself, so getting the Pep files to fit properly can be a challenge.
I realized that luckily before I've gotten too far into my build. What I've started doing, is printing the foam files out in pep, then just mocking them up by cutting out the pieces on cardstock, and taping them together real quick to get an idea of the finished dimensions of the piece. From there, I can see exactly what I need to adjust. I also check for better ways I can design certain pieces. Some pieces and angles just don't translate very well from the model to foam. From there, I basically design and create my own foam templates, and build from those. I'll build one piece first as a tester, and if all goes good I just build the second one. If there are some small changes that need to be made, I'll adjust accordingly, and then build again.
In the end, its a much longer process, but overall the general shape and design of the piece is far superior. Well worth it in my opinion.