I've uninstalled P3Dv2 until L.M. can smooth things out and Orbx can correct the "objectflow" problems, so forgive me, I'm working from memory.
In SimLauncher v9.2, select the option to edit your profile. When you're in the profile and have the various pathways showing, look towards the bottom the edit screen for "startup program accepts flight as command line parameter". The box is "ticked" by default; "untick" this option.
When SLv9.2 launches, it looks for ".flt" file, can't find it and then loads the "fxml" as default. Unless you've modified the default flight, you'll end up on the runway at Norfolk, VA. I never used a .flt file to load as default.
I never created a new flight plan and tried to load, but see no reason why it shouldn't work.
I used this method rather than running the P3Dv2 Scenario since I was testing several different scenery configs with specific scenery installs.
plug_nickel