AI Aircraft Filter

I recently finished making the transition from FS9 to FSX, and things are going well. My AI in FS9 was pretty much custom built and very extensive, and this is the only thing that's struggling during the transition. As an experiment, I've started using the traffic toolbox dll within FSX to "filter" the AI aircraft in heavy areas; for example, if doing a flight from or to KPHL, a few minutes before the FPS-sensitive approach I will go through the list and delete any AI aircraft that isn't going to or leaving KPHL. This can drastically cut down the number of AI planes being processed by the sim (from 500+ to 150 or so in the worst case at really busy airports), letting us keep 100% AI at the target airport and still keep decent frame rates. This is in contrast to the FSX slider, which is a global setting.

Doing this manually works but time consuming, and after a few minutes more AI aircraft respawn and the performance starts dropping, meaning that if you want to keep the effect you need to keep cleaning out the AI traffic every 10 minutes or so, worse in busy areas.

How difficult would it be to make an external program, such as AIsmooth or AIseparation, that does this filtering automatically? For example, just type in the code of the airport that you're arriving at or departing, hit run, and this program would connect (presumably via FSUIPC) and the delete AI aircraft that don't meet the destination/arrival criteria. I think this would be very worth doing; for example, if I do the filtering just before turning on final at JFK I can arrive in a complex aircraft at 100% traffic in bad weather, while keeping the sim smooth, before it quickly deteriorates as I'm unable to constantly keep deleting new offending aircraft.

Any ideas?

thanks