I borrowed the default GA flightplans from UTL, or Ultimate traffic, either BGL. I then use AIFP3 to assign new aircraft that I borrowed from ORBX. Just try to use similar speed aircraft. Also delete the commercial airplanes from list using AIFP3. Works great and covers entire world. (Be sure to cancel assigned flightplans for commercial, AIFP3 will prompt you. Put the new bgl either in your root scenery/world/scenery or your AIG manager flightplan file.