I'm not an expert, but I did recently attend a B&C scoring seminar. The tip-to-tip and greatest inside spread measures are only listed for interest sake, they are not part of the score.

If I understand your question on points that are scored, an "8-pointer" receives G1, G2, and G3 scores, but no G4. A typical 10-pointer gets a G4 but no G5, and so on. In other words, you don't get to double count the end of the main beam that makes the final "point". Remember that you took that measure already for the main beam's score.