hi Mike (again, lol)
maybe try to do them like the end of a very large bomb?
do the radome tan,,,,,,,roll up some paper and tape combo, push the tube up onto the nose, do the white, make a larger tube
or a combo thing,,,,,,,,the "back edge" of the White is on a taper so that tape can be put on, and then cut your line,,,,,,,,after that tape is on, you can do your radome color, then the tube thing,,,,,leaving you with your white area open ready for paint with tape on the back side and the tube on the front edge
I hope this is clear enough to visualize,,,,,,,I "see" it right in my head, hah
Rex