This trouble have been basically sorted out by two Italian guys, Fandango and Goldorak who found the way to make it very simple to create any map with the P-3 starting the mission on the runway.
Simple and effective.
Actually you can even select weapons load out before take off.
I tested it and did a mission the same way and it works flawesly.
Great Job Fandango and Goldorak
They posted a mission example on the CADC where you can download it.
HERE
Amazing