Do some searches on https://discuss.ardupilot.org
There was some high speed run plus high speed mission.
An issue is the angle of the GPS antenna - you need 2 GPS units mounted at different angles (to suit forward flight with a high lean angle), or a helical antenna.
Read through the searches you do on Ardupilot.
Theoretically you could use a servo to tilt the GPS mast, like you would with a single axis camera gimbal.