BadWolf - it's frustrating for the rest of us that so many US planes don't broadcast meaningful ID's, so it must be doubly-frustrating for you guys actually there!
We do have round about 300 different logos for N numbers, and we only have them because at some stage they have used their N numbers as Flight ID's. Some of those logos will be for large fleets like NetJets, so if you are prepared to do lots of copying, pasting and renaming of logos like that, you might be able to increase your logo count!
Having said that, I have in the past proposed to AirNav Development a new Logos routine which would get round this problem. Only time will tell whether they will incorporate that scheme in the new release that they are now working on.
Rod