I was thinking about using a razor for a really sharp, straight cut. But then I just realized I wouldn't be able to do anything about the threaded seams, they would eventually start to come apart. Well, I guess I could fuse them.
Be careful if you put anything on the seams. Back in the day I did the same thing and used aquaseal on the seams. The aquaseal didn't stretch so it had to break or be carefully cut so you could get the suit on. All of those little breaks/cuts scratched the crap out of my arms.