So I can now beat Attack of the Fan Girls, but I can't figure out how to get a higher score in the end.

Originally I thought that I would lose points whenever a fan girl made it to the mansion, but I don't ever seem to lose any from that. Do I perhaps get more points after each level if I have some cash saved?

Well the more girls you hit the higher the points. So if you win by just the skin of your teeth you'd have less points....I'm sure other things figure as well...but I do not know what.

To level 5 test:

7120 - Close - No spare gold.
7120 - Far - No spare gold.
7120 - Close - 200 Spare gold. (Far would be ineffective)
6540 - Wave 5 (10 units) getting through.

Just did it. Any other possibilities I can test?