Udo,
I know what you mean about fiberglass, I cannot work with it without getting it all over me and anything close. I watched one of the very best fiber glass guys that ever made a glass part, Wayne Hartman, make a fender mold once and he never got resin above the first joint on his fingers! never broke a sweat, never got anything on his shirt or pants! By shear luck I do remember some of his methods but never was able to be as "neat" as he was.
I know your mold will turn out good parts, it may take some sweat and swearing but my guess is that they will look great. As my favorite saying goes, "When you learn by experience the test comes first and the lesson comes afterward."
Rex